I think Regina must have always remembered her FTL life. Otherwise I don’t know how she would have known how to access her heart vault underneath her father’s “casket” in the cemetary. I do think that probably as time went on (well, I guess not really) she may have gotten “comfortable” with time standing still and fell into a pattern of being large and in charge as mayor of Storybrooke and Henry’s mother; just gotten used to the curse working. And then Emma showed up and suddenly Regina has to face the facts that the curse isn’t going to go exactly as she has planned. I think Rumple was just sitting tight waiting for Emma to show up on 28th birthday – there wasn’t any reason for him to confront Regina or let on that he remembered because nothing was going to start to happen until Emma showed up and he knew that. I honestly think the writers HAD to have Rumple remember his FTL. I don’t think it would be much of a show if Regina was the only person in Storybrooke who remembered FTL and the curse – I think it would fall short of storylines. Besides what Snow did to tick the EQ off, the power struggle between Rumple and the EQ and Gold and Regina is the central element of the show.