strange brake behavior

While wheeling a few days ago, the jeep was at an extreme angle and
the engine was about to stall. I was driving off a ledge using the
brakes.  I realeased the brakes to see if the Jeep would roll forward
a bit and then when I pressed on the brake pedal again it went to the
floor with no resistance, I let it out and pressed again and it went
down most of the way but I think there was some resistance just before
the floor.  It seemed like the brakes where being kept applied despite
my foot being off the pedal.  I shut off the engine and restarted and
everything was fine for the rest of the trip and it was also fine the
next day around town.  There was no fluid loss, the reservoir is still
full.  Any ideas what could have caused this?

Thanks