odd lurch at start up

so i got in my truck today to go to school and put it in drive, usually when i first change it from park to drive and take my foot on the brake it moves at a pretty good rate considering its still on closed loop and im at 1.5 k rpms at start up, but today i put it in drive and i just sat there and then all the sudden lurched forward with a weird clunk sound and then i was fine. Im thinking it could be my brakes but i cant really tell. it was pretty wet out from condensation but i dont really think just that alone could cause this. any ideas?

 

thanks never had this problem so i was a little worried

 

More of . and more , or even ;. J/K X2 with whippersnapper.