My now paranoia happened to me on my first lesson
. Climbing out at Vx, the pax door popped open and out at 100ft AGL. Didn't bother me until the CFI physically leaned WAY out of the 152 to close it & I realized my instructor was dangling out in open air, with the only thing between me and an unscheduled solo at 0.2 hours was a fraying 20 y/o lap belt.