I've had a few matches end like that. The fight seems to be going smooth, and everything seems to be going right, and then it pauses and disconnects in the middle of what looks to be a fairly even match for me, and the opponent. The kind of thing a competent player wouldn't give up on.
So this seems to explain what was happening. The game De-Synched on each side. I believe I've only ever seen this happen in my time with exhibition matches, and not with ranked.
SFxT OBVIOUSLY did this a whole heaping bunch of times early-on, pre-patch. I'd see my friend (who has very good fighter reactions) constantly "react" to things I DIDN'T do, letting me know that wasn't exactly how things were suppose to go. You'd catch things such as over-walking to bait moves, sweep-loops that the opponent should be able to react to (that suddenly turns into a rollback instant-DP counter), fireballs that were called out, but never thrown, etc. 've seen such things also happen in laggier match replies from KoF XIII on 360; What I fought was an OK match, the replay showed either character often standing still and tossing out normals without reason; making it look as if one of the opponents went brain-dead after some time had past.
Anyone who'se played this game while listening to comments from the other side, can tell it is in-synch a vast majority of the time. I hope this issue can be refined out of the game, but this is hardly outside the realm of expectation for "fresh" Fighting Game Netcode. If anything, this is closer to what I expected (with a few hiccups and oddities), than the "IT'S AMAZING AND SOMEHOW BEATS CAPCOM AND NACMO ON DAY ONE!" stuff we've seen before.