There are loads of things that can cause bumps on your
lips - irritation, allergic reactions, dermatitis, eczema, Fordyce spots, among a lot of other things.
The only way you'll know what is causing yours is to see a doctor when you have them. If they think it's a cold sore, make them do a culture or PCR swab on it to know for sure.
Cold sores are caused by herpes simplex type 1, and about half the adult population has it.