It could be a bug bite. If it doesn't go away within a few days it is probably something else.

Does she eat/drink out of plastic bowls? A lot of dogs get "pimples" from eating out of plastic bowls. If so I'd swtich her over to a metal or ceramic bowl, it may take up to a month or so for it to dissapear.

If it's still there in a few days & she doesn't eat out of plastic then I'd get it checked out. It could be an ingrown hair/whicker, a cyst, a weird wart or a tumor of some sort.

Good luck & keep us updated please.