A lot of good shops require you to setup an apt for diagnosis/repair. Plus they could of thought he just wanted to know what the problem was then say thanks, and fix it himself. They days of just walking into a shop for service are about gone. Unless your going to jiffy lube or something. The last 2 times I had to take a car in I had to call, and set it up a few days in advance. Both times I had no choice. 1 was warranty work, 2nd was AC work.

Don't take it too personal it's just business. They would rather be utilizing 100% of their techs time working. If they had enough techs to take random drive ups, then they have too many techs (in their eyes).