why so sudden

I know that you atleast once have been in a scenario where you felt that you saw a person from a distance or just in a glimpse and then felt that you met him/her sometime before or you really know them but just not sure if it's really them.. Well I saw this guy today and thought that he really looked like the guy whom i had crush for a really long time ago.. Let's call him M.. Maybe you heard about him in the beginning of my blogg but yeah i had a crush on him when we were newly transfered here in Sweden.. I met him in the buss. Well he goes in the same school as me but i don't get to see him that often in school. The only time I see him is in the morning when riding the buss on the way to school.. But not everyday either cause he also drives a car.. So yeah.. What i want to say is that since i am not sure if that was really him i was really curious if i he was really M and if i said hi and asked if he still remember me.. Will it made a difference? Now i can think of what if i reacted in a different way...