AIBU to not offer a drink to workmen who say this or similar 5 minutes after arriving? 
it pisses me off! If you want a drink then ask for one, if you had given me a chance I would have offered you one but not 5 minutes after you turn up while you are still unloading the van and haven't even started doing anything! 
I always offer a choice of tea, coffee, cold drinks. I make sure I have biscuits in, I've even made homemade soup for workmen in the past when they were working on the garage in horrible weather!
So it's not like I'm mean when it comes to that sort of thing, comments like that just get my back up and then I don't want to offer them anything! So AIBU to reply "yes it must be" and then not offer a drink?