The Miami episodes of Jersey Shore premiered on MTV just one week after the cast began filming again in Seaside Heights, so what we're witnessing now on this season are their raw reactions to reliving painful moments from the past.
On last night's episode, it appeared that Sammi was just being a bitch toward Ronnie for no reason—since illogical bitchiness is what we've sorta come to expect from her—drudging up shit from months ago when they were in Miami. However, the cast moved into the Seaside Heights house around July 22. The Miami season premiered on July 29, and judging from the time lines on their various Twitter accounts, they were permitted to view those episodes. So it would make sense that around this time, Sam was finally witnessing what she'd only read about (in an "anonymous" letter): Ronnie's promiscuous night out in Miami, ending with him cuddling in with Sam in her bed. On the After Show, Ron admitted that while he had eventually fessed up to some of his blunders to Sam (off camera), he had been so wasted that night that even he didn't remember exactly how much of a dick he had been.
Many people wondered if Jersey Shore would still really be the same, considering that the cast had rocketed to stardom after the first season. However, these people always thought they were the shit, so their new-found fame didn't seem to affect them all that much, at least as far as the episodes and storylines are concerned. I mean, look at Vinny, working back in the T-shirt shop, surrounded by Jersey Shore-related merchandise ("I heart Snooki," "Beat Up the Beat," "Never Fall in Love at the Jersey Shore," etc.)
He barely seems to notice, and weirdly, there weren't many customers around to notice him.
What's more interesting is that instead of the fame affecting their lives—and this season—instead the show itself is. It can be assumed that much of the drama from here on out will be based around the shit-talking they did in their interviews about each other in the Miami episodes (even if the acknowledgment of this is edited out of these Seaside episodes). So for them, the past is not the past, but rather, a hit show currently airing on MTV.