Woodstock? What's Woodstock?

Why does John Stockwell (Michael Harlan) say "Woodstock? What's Woodstock?"

He says it at the end of the movie to Dennis Hopper (Bob Roberts Esquire).

My interpretation:

I'm assuming the reason they put that line in is to convey that the timeline is now screwed up and Woodstock maybe didn't happen in this "universe".

One could also assume that implies that Harlan is a young guy that doesn't even know what Woodstock is. However, I think this is a far stretch seeing as how this movie took place in 1985 and he's a teenager in high school, thus he would have been born within a few years of Woodstock. Is it conceivable that teenagers in 1985 didn't know what Woodstock was?