That stinks. I've left or lost a few things while hunting and most of the terrain isn't worth the hike back in to look. Gooseberry got a fair bit of traffic when I was there in September. Hopefully an honest person found it and it gets back to MM somehow. If you don't end up finding it and are interested in a slightly used bull pac frame and bag, I've got one that I'll hock cheap. It's packed out a handful of bulls and bucks so it has a few scuffs.
Jim