It doesn't look too bad.
Could be a simple reaction to the stitches..if the wound was oozing,I'd take her to the vet but if it's clean and dry,I wouldn't panic.
When are they due to come out? If you have any doubts give the vet a call and see.
I wouldn't put a cover on it,letting the air at it is better and she's probably just eat the bandage anyway.
It actually looks like a very neat incision..
Sharing my sofa with Holly, Ivy,Lilly and Hazy.. and never forgetting our beautiful Daisy who reached the bridge too soon.