driving to work this morning and came to stop at a quiet t-junction just off the road i live on and the brakes failed.

foot went to the floor but nought happened

pumped it a couple of times and locked the rears up and managed to stop. pulled into a stop and just before i got out to check for leaks i pumped it a few more times and i had a pedal again.
drove on very carefully and all was fine for the rest of the journey

i'm assuming either moisture or air in the front lines somewhere, does that sound right?

cant be a leak as the pedal came back and its not a sticking component so must be the above?

not done it before and not done it since - i wondered if it was because of the damp morning as i've just got the motor and have only previously driven it on hot days?

any ideas folk?