Engine rocker blow out?

2012 Prius IV started making rattling sounds which, after replacing coil pack and spark plugs, my mechanic said was due to a warped head gasket. Toyota dealer found coolant in one of the cylinders "confirming" the same.

I say "confirming" because I never experienced any of the other common symptoms of a warped head gasket- no white smoke, no overheating, and when I removed the valve cover found no sludge oil/coolant mix.

I started tearing the engine down to go after the head gasket myself but upon removal of the valve cover discovered two rockers setting on/next to one of the cams.

Any thoughts as to why this might have happened? Still need to remove the head for further findings but curious if there are any thoughts on the matter. I have some theories but won't bother to elaborate to keep this a bit shorter.

TL;DR found 2 engine rockers on/next to a cam. Why might this be?

Thanks in advance

 

thanks

I'll get some pics this weekend and post

 

For further background, a few months prior to beginning teardown of engine it was intermittently- almost exclusively upon startup for less than a minute at a time- misfiring on one cylinder. Immediately prior, and the impetus for the teardown, it was misfiring on 3 cyclinders and had a camshaft position actuator fault.