Open Incision after spaying, vet says it looks "ok" ? (WARNING graphic)

After about 6 days of having this stray cat spayed by the local Animal Services TNR, I noticed her incision a little open. (I released her 4 days after the surgery to avoid this complication, but here we are)

So, I took the cat to a private practice this morning. The doctor sedated her and I was able to take this picture below. 

According to the vet the incision was a little open, but it was "ok".  That the cat will be fine and concluded that it was best to let it be. (meaning not adding more sutures.)

She spread a little Vaseline over the incision and advised that I keep her indoors for 24hrs before releasing her again. 

I know you aren't vets, but maybe you have seen something similar.

I wanted to know whether you think this needs the opinion of another vet or I should let it be, as suggested. 

Here is the picture I took this morning. 

Opinions appreciated. Thanks

I understand your concern. It doesn't look bad to me either, but just to ease my mind, I think I would ask the vet to put a another suture in there anyway. The wound doesn't look infected.

It doesn't look infected at all.  I think she will be ok.  

Thanks for replying.

it might look ok because it may have come open in the past 24 hrs and may be too recent to show signs of infection?

 i worry it could become infected soon

It looks OK. It appears to be healing from the inside out, I don't think it's in danger of coming all the way open or getting infected. Of course keep an eye on it. . .the signs of infection are seeping pus and angry red irritation.

For how long should I keep her inside before letting her out to the heat and tropical rain of south Florida?