I bumped into (at 2m away!) someone I met a few times a couple of years ago, we chatted for a few minutes. I almost asked if he fancied a coffee some time but didn't. I'm considering emailing him a week later to ask? It seems like it would have been casual if I had asked at the time or immediately after, but a week later is different.
I get that I have made this seem a big deal but it is very much out of my comfort zone!