Recently turned 18, all of a sudden have an old medical debt?

Recently turned 18 and all of a sudden I’m getting letters and the occasional voicemail that there’s like $30 of medical debt from like ~middle may.. I’m covered by my parents’ insurance and regardless, that should’ve already been handled and paid for during whatever clinic trip it must’ve been.

It’s a bit irritating and concerning that I’m getting “debt collectors” calling me for $30. Both my parents and I are confused as to what it’s even for/from.

So, kind of a vague question, but any insight on what this may be and what action to take?