In another thread someone mentioned that you don't tip the owner of a hair salon. Is that true universally?

I have to admit that I'm often unsure about tipping and there are many situations in which I worry about over-tipping or under-tipping (except at restaurants where it's so clear cut).

I get my hair cut by the owner of the salon and I have tipped her in the past. Is that odd or unneccessary? (not that I'd feel comfortable stopping now, but I'd like to know for if/when I ever change salons)