Thanks for the tidbit, it helps my disposition a little. This attack was something I wasn't used to so I didn't know what to expect.
The incidence of AFib does go up with age, mine started at about age 60.
As you are not in AFib 24/7 the likelyhood of it causing a stroke is rather low, about the same as the general population. That said, I'd suggest taking an aspirin a day with a meal, if it doesn't give you stomach problems. Of course, it you are taking any medications that restrict the use of aspirin, then follow those instructions.
I take Warfarin and aspirin, but I have chronic AFib, so the chance of it causing a blood clot is too high to ignore, still it is only about 3% a year for me.