DILO2001GT

i filled my airbag the other day before i went to the track and it was full, capped the top off and then went to the track. when i got there the airbag was empty and there was no airpump at the track to pump it up. do you guys think it was the hour ride there and it slowly leaked or you think its something else? tonight im going to fill it and just let her sit for a bit and see if it stays in. if so then i will just bring a pump to the track. and hope the air stays in for the run and just fill it after each run.