I guess this is what I'm trying to get at - does this cause more than cosmetic blemishing? A lot of replies seem to be, "I don't like it either, but it's not a huge deal." To me, that sounds like the greater offense is the disrespect. I'd prefer that over "Now your tanks are going to rust and pit through the bottom within 2 years."
Your tanks should be fine and might even outlast you! BUT...still annoying to say the least that they were so careless. I have to agree w/Doc Intrepid wholeheartedly. Get a cart if you are that lazy! I would bring it to the shop manager/owner's attention and ask them to please treat your gear with more respect. Good luck!