Sings of infection after spay?

Tango was spayed last Monday and this morning I noticed that on one side of her incision is a bit swollen and hard to the touch. It does not bother her, she will let me touch the hard area. She is eating, drinking, playing normal, though still a bit more tired than she was before the spay. The incision itself looks fine, no redness, healing evenly, ect.
The only thing is that she has been running around a bit more today than she has been.
Could it be a bit irritated because of the playing? Is this normal? Vet trip tomorrow?
Any advice appreciated! Thanks!

Signs of infection are heat (localized or fever), redness, swelling, drainage and pain. If pain, redness, drainage and heat are absent, then the swelling is probably due to a reaction to the sutures. This is not an emergency. My vet told me to expect it, but I was surprised to see how much swelling there was and took my kitty in anyway. But is was just a suture reaction and went away in a couple of weeks. You should call your vet to be on the safe side, but expect to hear that it is not a problem. Becky

Thanks Becky!
I feel much better now
I'll call in the morning just to be sure, I had a feeling she was fine, and hehe I do expect to be told that she is now! Thanks!

I was actually pretty embarrassed about this. I called the vet and they told me it was normal. But I insisted it was abnormal, I had never seen it before. They told me to bring her in, and it was normal. So I was pretty embarrassed. But I have had cats spayed before and never had it happen. It was pretty big swelling, too. But it went away, just like they told me it would. Becky

Thats why I was so worried! It never happened with Cola or any of my Mom's cats
But until I can be completely calm about it I'll still call in the morning