If such incidents were to repeat themselves, though, someone else would likely end up being the target next time and hopefully would notify the police as well. With more reports from independent people maybe they can shut it down. The bad thing is that the laser is so elusive that someone can really get injured before this is stopped.
I don't know your situation, but if it were me, I would probably approach this head on... as in, if it happened again, I would probably head FOR the source (while doing my best to shield my eyes). I am willing to work on the assumption that this is NOT a weapon sight, and even if it is, that it is NOT attached to a weapon in the dorm. Obviously this is a risk.
If that sounds too dangerous, then I agree with LeeG. I would start with the RAs in the dorm, or even the responsible GA. Failing that, try the campus housing office. File a written incident report, if you haven't already. While I'd hate to see some kid's college career jeopardized by what is, in all likelihood, a thoughtless moment of stupidity, there is value in teaching the lesson that actions have consequences.