I am generally pretty easy-going about things but I really don't like being called just "dad" by my kids' teachers!
If you're not sure what my name is or what to call me, why don't you just avoid saying my name like I did with my mother in law for the first six years of marriage ha. (Now that we have kids, I call her Grandma.)
Do the teachers at your school refer to you as "mom" (or "dad")? Or do they refer to by name (or avoid saying any names at all)?