rocker arm issue!

[v8power]

for the second time now I had the same rocker arm come off on me, nothing breaks just pops off. any one ever have this happen? im confused here. i have less than 150 miles on this engine and have checked the rockers a few times already.

BTW when i set them i go 90* at a time and finger tighten, 2 full rotations and give them a .25 turn.

 

[80montecarlo]

are the screw in studs or OEM press in's

 

[v8power]

screw in. here is some pics, i just put it back on a re checked all of them, the rest are fine. i was going to put the valve cover back on then i saw this...