Yeah, the fact that the Leonard-Penny incident resurfaced from last ep. had me thinking.
My gut feeling... that the continuation across episodes has weight. Incidents introduced in an episode tend to be neatly wrapped up by the end of it: it makes it 'digestible', with episodes easy to watch respectively. When theme quite explicitly carries on? It's less of a 'surface' plot to bring out characters than something that'll influence character development as the show progresses.
Still, I think with the wide audience BBT receives, and also for repetition sakes, another wedding theme -- which woul