Gearbox bolts

Been having a few issues latley with selecting gears and juddering, ive got a 4 paddle so assumed there was something iffy with the clutch / fly wheel.

Turns out i only had 2 bolts holding the gearbox on....

How dodgy is that, I know they where in there as ive recently fitted a stage 2+.

Its it possible for them to come out due to vibration or have i just not done them up tight enough.

Any one else had this ?