Funny thing happened the other day...

So I was debating whether or not to post this event, but considering it's so rare and that I had little idea of how to respond, well... Maybe you have some advice (or similar stories) to share.

Yesterday afternoon I was making the long trek down to the mailroom to drop off a package. Two people were having a conversation; I had to pass between them. As I passed, the man said hi really loud. The woman nodded and smiled. I smiled and said hello. On my return trek, they were still talking, but this time nothing was said. I went back to my office and settled in for a short afternoon. About 20 minutes later, I hear someone coming down the hall. Then I hear a man's voice say, "Hey, good looking." I jerk my head to the doorway in time to see the same man going by my office... is he talking to me? how do I respond? I was slightly offended by his greeting and the first thing in my head was Sexual harassment?? I broke out of my stunned (and probably pretty confused) stare enough to say hey. Thankfully by then he had gone on into someone else's office.

?????

This obviously caught me off-guard since people (especially men) don't usually greet me with a hey, good looking... Isn't that line reserved for movies, clubs, and definitely NOT for the workplace??