Baby Lip sore? (Pic inside)

My baby was running a little temp this morning but it's also 90 degrees outside so I wasn't sure.

Anyway just now I notice this on the inside of her lip. I thought maybe she bumped her lip at the sitter or something but it looks like a sore.

I have a no drinking off of adults policy but I'm afraid someone isn't following it. Maybe I'm just being paranoid but what do you ladies think it looks like?!