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did the 3.7 gigs come out of no where, or did it build up?

Not really sure. I had 3 gigs of music on my phone, and then i clicked the box to make it "higher quality" or whatever and then before i even synced it my music disappeared and I had to re-sync it and now have that fat almost 4 gigs taken from me.
 
I had a similar issue happen to me last week. I originally had about 300mb of 'Other' on my phone, and my music was set to 128kbps, I then unchecked the Convert button to have my music be higher quality, and boom, I had almost 2 gigs of other.

So I then did a complete restore (from a back-up) and I re-synced all my media back on and this time, I was back to my original 300mb of other, and all my game/app data was still the same (didn't loose anything).
 
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