3 Month Old Has Birthmarks Under Eye that Come and Go?

Hi! My 3 month old daughter has had two little red marks on the side of her eye--in the exact same place every time-- that come and go. Sometimes I can see them and sometimes I can't depending on if she's cold/hot/crying/etc. and it's been like this since she was born. They are like tiny red splotches. What is this? When I ask the doctor they are never there at that time so he's not sure what I'm talking about. Do any of you notice this on your babies and do you know what it could be? Is it dangerous? Thanks so much for your advice!