Since someone has been asking about this whole canon thing recently:
How come Glenn never mentioned he was with other survivors (as in the video game),neither in the comics( correct me if he does talk about it at a point in the comics I'm not at yet) or in the TV show? Sure you could say: he just never mentioned it but do you really think someone wouldn't do that?
Edit: I got the wrong idea from reading the article about "Glenn (Video Game)". So no worries, everything's fine :D