That is most likely what it is. Is it around where she got her shot? Usually the DA2P + shots are given near the shoulder area. That is where I gave them when I was a vet. tech. They react the those sometime, especially with the smaller breeds. If it is in the hind leg area - that is the rabies shot and usually we do not see any reaction (bumps) from them. If yes for the shoulder area, it can take, for some, a week and half to go away. If it is not where her shot is - you can call your vet to make sure if you need to bring her in or not.
Best Wishes with her.
T.