what's going on with this guy to send a message like this out of nowhere?? :S

I've been dating a guy over the summer for several months but it was a bit crap because overall he was flakey and wouldn't even be interested in meeting more than once a week (always some sport and job excuses). We sort of had this falling out/'break up' (not that there was anything official to break up) some six weeks ago and I thought that was it. However, afterwards, we've met once, which was comfortable (I do like him) but still didn't feel like there was any real connection (I am totally unable to get a conversation out of him). That was three weeks ago, after which we barely exchanged any words at all and I actually deleted his number and sort of repressed him from my mind (I usually always have to initiate things, and he takes literally days to reply...again, crap for me; all pain and no gain). Then last night I get a message along the lines of "I'm sorry I'm a jerk. You don't deserve it since you're one of the nicest girls I've met. I just don't think I'm the right person to be with you since I'm so selfish and don't know how to change that yet."
I honestly didn't know what to think. I was both amused, sad, and confused with regards to its content and timing. I didn't reply to it but I can't imagine that he'd dwell on something for days or weeks to write that... why are guys so weird???