As a young, and young looking quasi-professional, I certainly get my share of queer looks when I get in line to board with the First passengers or Premier passengers. I don't understand why people can't get the fact that not everyone who is a frequent flier is 40+ wearing a suit.
I see lots of threads about clothes to wear on planes as well- I usually go for polo shirt and jeans, so I'm a bit out of place on the plane with lots of business travellers, but if I wear business casual to work, they ask if I have an interview. Ah, the joys of the manufacturing world.
Back on topic - I'd have decked the guy if he grabbed me. What a jerk.