Gong Sound on Cu Chi

Post patch 1.0.1 there is a audible gong sound on Cu Chi, it is the only place I have heard it so far and I was not the only one to hear it. I think it is either an RPG or the M79 producing this noise, but I was always too far away to exactly determine what is causing it.

Gong noise heard 3 times:


Someone else comments on hearing it (to prove I'm not insane) @ 01:14:



Gong Sound on Cu Chi