Speaking as someone who managed a half-dozen bike shops in three states, the simplest explanation is that the employees had recently been lectured/threatened by the shop owner or manager that if they didn't stop ignoring customers they'd be looking for a new job.

As for visiting two more shops and receiving the same crappy treatment, I think you probably saw it because you were looking for it. Go in with a sour attitude, you'll come out that way, too.