It does look extremely swollen. But I think it's more of a tissue irritation that internal bleeding...with bleeding I would think the whole belly would be hard and distended. Here's a thread that has a picture in it that is more typical of what post spaying looks like in my experience.
Does it seem to be causing her pain, is it tender? Is the incision clean or is it oozing? Don't know what to tell you in terms of going to the vet. If it's painful/tender or oozying I would take her in. But it definitely bears close monitoring.
Holly, Misty & their friend, Jake, the dog.
Onyx, Callie May, Maggie & Kobi forever in my heart.
Yes, I know I need a new signature pic...someday...