lump at incision site, 9 week old, spay

This doesn't look normal to me, she was spayed last week.

That does look a little bit unusual for a spay scar.  I'd call the vet's office and let them know what's going on.

Looks like a hernia I'd get that checked ASAP if the lump is firm as that could be an internal organ. It could just be fatty tissue coming through or fluid either way I wouldn't delay getting her back to the vet. Looks like a couple stitches came loose inside.

hexiesfriend
We are definitely taking her, calling the vet tomorrow. I'm just very worried about her health having to wait at all.

That looks like a seroma to me, which is not an uncommon minor complication from a spay surgery. They often show up at the very bottom of the incision like that. They can be caused by moving around too much after the surgery, or because the tissue is irritated by the sutures. There isn't any way anyone here can tell for certain whether it's a hernia or a seroma from the picture, but a vet will be able to feel her abdominal wall and tell you one way or the other.

If it's a seroma, it's not anything to really worry about. They generally go away on their own in a few weeks. If it's a hernia, that's a bigger deal, and the sooner it's treated, the better the outlook. When my kitten developed her seroma - 5 days after her spay - I took her to the emergency vet to confirm. If that's a possibility for you, maybe you could consider it? Our emergency vet doesn't charge much more than the daytime vets here, so maybe that's easier for me to say. The small extra charge was worth the peace of mind, and if it had been a hernia, she would have been in the right place.

Has she been pooping regularly, and is her appetite good? If it were an intestinal hernia, which would be the most likely type of hernia, you would expect to see those things drop off. If she's doing fine with both of them, then that points more towards a seroma.

flowerdew
I don't think we have an emergency vet around here but I'm asking tomorrow, or get the soonest appointment. (We just recently moved onto an army post)
She hasn't been eating much but seems to be going potty normally. It doesn't seem to bother her and I checked to see if it were firm or soft and it's soft (squishy) no pus, no odor.

And she's been very active. Since I brought her home after surgery.
I had to lock her out of my room to keep her from jumping on my bed.

No pus and no odor is excellent. Also no redness. Besides the lump, her incision looks like it's healing very well.

Just call the vet first thing in the morning; I'm sure they'll fit you in immediately. And in the meantime, try not to worry too much. Try to keep her quiet if you can (I ended up having to keep my girl in a closet for a few days), and keep an eye on her eating and litter box usage. Like I said, the vet will have to tell you for certain what it is. But from the picture and your description, I suspect it's a seroma.

Sorry, I woke up fretting about my response here. This reply is less for you, pookalali, since you've already said you'll be getting your kitten in to see a vet as quickly as possible. It's more for the person who reads this later because they have a similar issue. I'd hate for someone reading my reply to think that it wasn't a very big deal and that it wasn't urgent that they see a vet immediately.

A lump like this should be considered an urgent situation. While it's very possible it could just be a seroma, no one can tell by just looking at the picture, and if it's a hernia, your cat's chances of survival and the amount of money you will have to pay to ensure her survival are directly impacted by how quickly she gets proper medical attention. Herniated organs, especially intestines, can atrophy very quickly. Get your cat to the vet as soon as you can.

Signs that definitely point to a hernia (ie: emergency room NOW, if for some reason you are wavering on it) would be vomiting, loss of appetite, lack of bowel movements, or if the cat seems to be in pain. Obviously, if the incision opens and organs protrude, you should know to go immediately to your vet, or to the emergency vet, if one is available.