Question about an ex?

well we broke up a little over a month ago and it wasn't the easiest split. a lot of our mutual friends stopped talking to him because he ended it roughly 2 weeks after we slept together and the pulled the "you are just too good of a friend" card (we were really good friends for two years before our two month relationship) well anyway now he's acting strange. He's always been the type to skip cl every once in a while but now it's just a bit much. ok so since the break up its been this weird cycle of he's everywhere then he just vanishes. from school and everything. i was out for a walk with one of my old elementary school friends filling her in on everything and we wound up at quick-trip to get a drink and right as we are walking in (and she's hollering about how big of a douche he was acting) he turns around and then even after he paid he just kind of stayed there until we got up to the counter with out drinks then after that he was gone for about three days. came back right before the renaissance festival and while on the trip he followed us for most of the day. it was like every 2o minutes he was there right behind us. it would have been different if he was with a few friends walking around and they just happened to all be behind us but he was by himself the whole trip it seemed and on the bus ride home he took the seat behind me and when we got back to the school he left and the skipped the next two days. when he finally showed back up at school he kept his distance until last thursday and this is the one that really weirded me out. well when i was walking home he made it to the stop light right in front of my neighborhood which wouldn't seem too odd except for the fact that the road was clear for him to turn but he didn't he just stopped there (he had the green light too) and had this mini stare off with me for a while until someone drove up behind him wanting to turn and then BAM missing again. hasn't been back since then. its just strange. any idea why he's acting like this