Should I log on AIM even if I got stood up?

I was online AIM yesterday and the guy who I like IMs me saying hello. But I had to go because I was going out somewhere. I told him that I would IM him back later on tonight and he said ok. So it's night and I log on AIM and he's not online. I wait for twenty minutes and he still doesn't show up so I sign off. It's today and I see him online. Should I IM him? But I kind of feel "stood up" from the other day. What should I do? I'm in high school by the way and he's a year older than me.