2003 Jeep Cherokee valve train

#4 cyl. Rocker arm fell out without no signs of any problems. Such as ticking or missfireing. No signs of wear or broken or bent valve spring, valve stem, rocker arm, and lash adj. Engine was running great and then bam out of the blue this happens. The lash adjuster has a little side to side movement in head but not mutch. What should I check?Do you recomend trying a new lash adj. And see what happens?