Nope, I wouldn't say you were overinvolved if you walked your child to their classrooms - especially if it was due to a safety concern. I can only speak for myself, but the parents I think are overinvolved are the types that have been mentioned in this thread....the ones that are staying in their child's classroom all day, eat lunch with them 3 times a week, get upset when the teacher corrects the child, etc. The ones who can't "let go" and let their children grow up a little.
I support my daughter's schools. I attend PTO meetings, sell fundraisers, make sure they have done their homework, ask about their classes, classmates, teachers, etc. but I do not feel the need to be there every day.