I would'nt read to much in to the fact that Abed seduced Annie easily, considering the rest of her love intrests on the show at large she seems pretty easy to pick up, Jeff basicly only had to say "Umm, im glad your staying" and share a hug to get Annie to move in for the kiss and get her obsesed with him for the start of season 2, Vaughn had to tell her some stoner-thoughts with her responding "You'r complicated" that pretty much sealed the deal and him singing and playing at the end of said episode is in my eyes considered overkill (funny tho), And one can only imagine the pleasantries the doctor and "pot-master" Rich exchanged with Annie while cleaning the freeway and river to get her to refer to finding used condoms, needles and a human finger in her "I love butterflies vioce", what im trying to say is that Annie is evidently the most inexperienced and gullable of the group and basicly anyone who has some "smooth" in them can pick her up relativly easy (Not Troy tho, refering to his strike out in the ep where Vaughn and Annie hooks up).
Tho i'd love to see how the cuple Troy and Britta would get along for the one episode theire relationship would last! 