I live in fear that they'll decide to stop coming and I'll lose track of them.
couldn’t you alleviate these fears by getting their contact info?
Social anxiety limits that. From my perspective, there's no logical bridge from "we run together once a week and chat over a beer after" to anything else.
Sure there is! "Let's skip the run and grab a beer on <other night here>". Or "Let's skip the beer and go on a run on <other time here>". Edit: Also, looooooooooove my Impreza because of the AWD, thing's pretty fun to drive, and is a hatchback and fits way more gear than I expected.
I'll keep an eye out for that kind of opportunity. There were only four of us this week. The other three are totally awesome (but there are other awesome people, too). It turns out they all hike, but none of us are big hikers locally. I'd love to meet some hikers that hike like me. I think some others from the group are doing an upcoming 20K. I am, too, so maybe that's a chance to expand how I know them.