Mac froze during a reboot?

Hi, earlier today, I was using my macbook pro (2009), and then, I went to reboot it. when I came back from taking a shower, I noticed that the computer had not gone to sleep (i rebooted it with the computer closed as i normally do). when I went to see what had happened to it, I noticed that it was abnormally hot, and when I checked what was on screen, I saw that my mac had never finished restarting. all I got was the apple logo and the boot up gear below it was stopped. naturally, I held down the power button to force it to turn off, but, when I went to turn it back on, it required me to hold down the power button for 5 seconds, then it went back to normal. when I came back from the store an hour later, the computer was fine. why would this have happened to my computer? its the first time this happened, and I would like to prevent this from happening ever again. I was thinking of taking it into an apple store to a genius bar session about it (since my MacBook Pro Restore DVDs are at home, and I'm at college for the summer.) Would they be able to help me solve the problem, or is it something I can fix without having any other boot disks? thanks for the help!