To me that is what appeared to happen because the trigger would not engage, but I guess it could have simply not been set, and the next round manually charged would have corrected that. That actually makes more sense....
Forward assist would not help, no trigger click, so your suggestion could be right on point.
This doesn't jive with your guy's diagnosis. Was the hammer still cocked (giving you a live trigger) after the stoppage or not? If your trigger were too heavy, you could have simply pulled the trigger again without having to cycle the action resetting the hammer.