Not an uncommon phenomenon by any means - and not surprising given the physical and emotional intensity of many LARP games.

In our circles it's referred to as Event Crash, and a number of the coping strategies here are familiar - particularly coming together later and telling stories about the event, both as a way to froth excitedly at people who have the context needed to understand the excitement, and as a way to contextualise the event's experience with others who were there.

The emotional impact that highly immersive games can have can't be underestimated, and any mechanism by which a medium can affect its participants so profoundly is certainly worthy of attention and further study.