At the risk of failing as miserably as previous responders, here's my thought.
Often, any more they do internal suturing so there's less for them to chew on and perhaps tear out, so that might very well be what this is. If it doesn't feel particularly hard and isn't especially painful, I would think it pretty much just the course of healing. Probable, with internal suturing, this is the means of limiting strain on the incision until the area heals because you know they aren't going to just laze around and take it easy. I had one, once, that had a c section and then about managed to gut herself by chewing on the exposed sutures, this, many years ago; and now, as I said, I think most are pretty much internal and self dissolving. if she seems to be developing any more 'size' to this hot dog, I would certainly call the vet. Or, if you absolutely, positively can't let it go and feel safe about the issue, call an emergency vet if yours isn't open and ask. My guess, it's normal.