Extruder nut where it should be or defect?  

Extruder nut where it should be or defect?

New owner of a Mini for the last two weeks and it has been printing great. Had a filament break trying to unload and I had to take apart the extruder to see why and get it out. Would not move forward or back and I could not pull it out manually. Found an obvious chewed up end blocking everything. Removed and that fixed that issue. 

Upon putting it back together, the three bolts that attach it to the X-axis mount, the upper right I noticed the nut was not on the X-axis part but slightly in-bedded into the extruder. See photo.

So only two bolts are holding the extruder to the X-axis mount?

Is this correct or is that nut supposed to be like the other two? 

As a side note, Prusa could eliminate these questions if there was a PDF with proper teardown instructions and photos. If that had existed, my question and fear of taking this apart with no manual would not have been much less.

Thanks!