Has my cat pulled out spay sutures?

Hi - I am fostering a darling cat who was neutered and spayed 12 days ago. As of yesterday, there seems to be drainage at the spay site - its sometimes a pinkish coloration and I'm afraid he's pulled his stitches out - as I wasn't present when he was spayed, I have no idea what kind of sutures they used. I'm keeping it clean until tomorrow (vet closed today) - he's in good health, eating, playing and being silly. The site is not inflamed or warm to touch, but there is oozing. How can I tell if he has knocked out his stiches or if this is an infection?