Originally Posted by Rommel49
Of course, there's also the fact that Larry can actually be the guy who ends up saving Lee from the pickup walker, depending upon the circumstances.
I think he probably kept quiet about it for the same reason Carley did in Ep. 1; the group didn't need additional problems and drama. Larry was just more direct/aggressive about how he phrased it than Carley was... even though they basically said the same thing on the matter.
I think he helps Lee mostly to save face. It would put him in a fairly bad light in everyone's eyes if he just stood there and refused to assist, even if he disliked him. He probably punched Lee in the drugstore because he and Lee were the only ones left inside at the time, and no one could know what he did.