Happened to Ghishlain and I, a while back during an Alexander run - DFed into what I believe was A2 with an FC mate or two and we recognized each other. I was too in a state of "wait, isn't that? o________o *Starestarestarestarestare-derps in FC chat to another FC mate that frequents the forums about it - then notes that everyone in the party is running off*" to notice that Ghislain had been speaking to me... rofl |||OTL *Ultra-derp*
But yeah.... slight state of "naw, it couldn't be o.o" disbelief on my end, but it happened.

On a roulette DF run, into Hullbreaker Isl several months back, I recognized Edwin Li. I was on one of my 4637850 alts, though, so not recognizable.... I didn't want to seem creepy, so I didn't say anything (though, maybe that in itself is creepy....? ionno...).
andmaybeyou'llneverknowwhichpugIwas *Maniacal laughter*

and lastly, it's happened to me, where someone recognized me - I was sitting in Gold Saucer, back a little after (or was it slightly before?) HW hit. I'd posted my Au Ra in the forums in the Au Ra thread, from the character editor they had in the benchmark ---- someone recognized me from that thread (I didn't recognize them, though... x.x). o_O Kinda surprised that I'd somehow stood out, at all, to be recognized. I'm not very good at speaking with random people so it was a little awkward on my side (sorry! T^T).... I ended up whisked away since a queue I'd been in had popped, though.

Other than that, there was one other person that I saw running around in open world, a few times, but I can't remember who...