So there are mobile auto glass guys fixing my busted window right now. Is it customary to tip?! I wouldn't tip at an auto shop for an oil change or stuff like that. Is it different because they're mobile?

I've got about an hour to get this figured out! Help me, GT, you're my only hope!

ETA: Thanks for the input! This is a decent sized company, mobile to home is a standard service for them, so no tip. I think I just heard thunder too, just in time! Whew!