Yesterday I took my '99 VFR out for a long "shakedown" ride. I rode all afternoon, covered almost 100 miles. No problems with anything on the bike, everything working as it should. So based on that long ride I figured I'd gotten the bike back together 100% correct. But today I took it out again for a very short ride and everything was fine until I decided to experiment with bringing the bike to a stop using only the rear brake (I wanted to feel what the linked brakes felt like when you used only the rear brake pedal). After bringing the bike to a complete halt with only the rear brake I put the bike in 1st gear and started off down the street again. As the bike began to roll I noticed right away that it felt like the brakes were still holding. So I got off the throttle and pulled in the clutch, when I did this the bike braked to a halt without me even touching either the front or rear brake. Then I noticed that the front brake lever was rigid, it was solid, unmovable. I couldn't move the bike at all, it appeared to me that one or both of the front calipers were locked onto the rotors. I put the bike on its sidestand and got out an 8mm wrench and very gently cracked open each of the front caliper bleed valves. This caused the front brake lever to relax and function normally. I got back on the bike and rode it the short distance back to my home. Once I got there I rode the bike around the block trying to make the malfunction happen again but couldn't get it to do the front brake lock-up thing again. Any ideas what happened?