[quote=@CorruptedShadow]
I'd say he'd act like a kid and tried to talk to him like a huge fan or something.  Maybe try and inspect the lightsaber, ask him to do "the Force thing" or whatever.
[/quote]

Bear in mind that not many people know Luke is a jedi-in-training yet. In fact it's another three years until Ben's appears to him and tells him where to find Yoda (not sure what the fuck Obi-Wan is doing for the three years between New Hope and Empire. Presumably getting himself a piece of Aayla Secura's sweet force ghost ass?)

As far as I can tell, canonically up until this point he's just been flying for Rogue Squadron, though it seems the new series of comics goes into some of the training he did before going to Dagobah to train with Yoda in Episode V. I might give them a look at some point.