I don't know whether anyone asked Roger about if he minded this being posted, but if not, as a matter of protocol, that should definitely have happened. Unlike services like Twitter, which actually encourages complete strangers to "follow" each other, Facebook, for many people, is more of a way to keep in touch with people they actually know, not just anyone.
While Roger is an extraordinarily nice man who probably considers LFaTs like us as friends in some ways, I'd hope he wouldn't mind being potentially inundated by a bunch of requests from G-R.net.
In the interest of full disclosure, I sent him a request as well, so I joined the same bandwagon. But I was thinking about it a little while ago and this occurred to me and I thought it might be worth mentioning for the next time someone from the show appears on Facebook or whatever the "next great thing" happens to be.