She went to the vet on Thursday and he says it's not the cancer again. Since the bump can change sizes varying on the day (from being almost non-existant to more of a BB pellet) and because it moves in the skin, he says we're just going to keep an eye on it. It does not stay put like the other bump. He's also not sure if it's just scar tissue from the surgery cropping up, since he did take out some muscle when getting the original tumor out.
The deal is to watch it and bring her in every so often to have it looked at, or sooner if things drastically change. She goes back in June for her yearly checkup with Baby so we'll see how things are then.
Mittens was awful mad at me though. She has to ride in a cage because of her tendency to get sick or do other things so on the way home I stopped at a gas station for a bathroom break. I came back out to find her facing the passenger door away from me and she would not turn around once the whole ride home (it's about 45 minutes). She truly is a queen.