I think husband is a long-term cheater...

I've been married for eight long years. My husband works a swing shift job. When he's on 3rd shift he always groom and dyes his beard. When I ask him why he needs to groom when he's on 3rd shift (it's late at night), he tells me his co-workers talk about his gray, but why they don't talk about it when he's on 1st shift (it's early morning)????? This has been going on for many years. I think he's cheating. What do you think?