before rconnely but, if the ammo was new factory stuff it should go right back with a well detailed explanation of what happened. If it was handloaded I would take another hard look at how it was loaded.
I have never heard of or seen a primer that popped out. I have had flattened primers and punctured primers but not one that ever 'popped' out. If you pressure was too high the primer would have flattened or been punctured. Under either circumstance, whether flattened or punctured, or popped, it may have made ejecting the case or working the bolt difficult.
The only reason I can think for a primer to 'pop' out after firing is if whoever loaded it used the wrong size primer. If you still have them check to see if they are the large rifle primer, they may have inadvertantly used small rifle primers instead and if they use a sealant in the case it would have stayed in until fired.
I'm sure not the know it all here but something doesn't sound right about this. M2C. Mikey.