I doubt it. Most guys will take attention from a girl in any form, whether it be online, tied around bricks hurled through windows, or as a series of stabbing attempts. If you understand comedic progression, you'll note that online was the least offensive of the series. We're off to a good start!
I'd say it's even BETTER to flirt in person, but if you haven't hung out since High School and there's no immediate way for you to get both he and you in the same place, then a poke is actually less creepy. Showing up in person seems a little presumptive.
If you want to be extra-cautious, you could always invite him to a friendly game of Mafia Vampires or whatever. Just make sure you parley the initial discussion into a real-world meeting pretty quickly. Ending up in virtual limbo both is easy and incredibly annoying.