How am I cutting my lip?

Not asking for medical advice here, just seeing if there is something that could be causing this. If it gets any worse I will be seeing my doctor.

With that out of the way, about a week ago I noticed two scars forming on the inside of my lip. They are both roughly an inch or so long, right above the mandibular canines. I’m thinking I must be cutting my lip on my canines but also wondering if there could be another explanation.

Biting your lips at night?

Must be something like that, but it just surprises me since it hasn’t happened before. I guess I’m wondering if there is anything that would cause someone to start doing that.