I noticed that, also, when I watched that episode of Dawson's. (my fave show!)
But I'm really hoping that them inviting Jack doesn't turn out to be some sort of thing where they choose him so they can haze him for being gay or for any other reason in later episodes. As my Understanding Mass Media teacher says, "no one wants to watch a show that tells the truth" (for ex, that most fraternities/sororities condemn hazing). So I'm just a bit worried that they might show the fraternity on there doing Animal House-esque things that most non-Greek viewers want to see. As Valkyrie said, though, so far they have portrayed the "Sigma Eps" in a positive manner.