Hey Ryltar --
Not exactly this same issue, but my "running total' balance has gotten off in one of my cash accounts over the last few weeks. I can't do screen shots right now, but I'll do so if it might help at all. The total in the bar at the top says $135, but the balance in the last transaction says $155. The only 'new' thing I've done in that same time period is try swipe-to-delete a transaction... (which didn't exactly work.... the transaction initially reappeared).
Anyway, two additional piece(s) of info for you --
(A) exporting my account to Google Docs, deleting the account on the Pre, and reimporting yields the same exact issue. (running balance off, actual end balance correct).
(B) swiping up all the way to the top of my transaction list (older in historical sense) and back down (to current) fixes the issue in the running balance total.
(C) Downloading account into excel and calculating the running balance yields the correct total.
I know this isn't a perfect bug report, but I wanted to let you know what I was seeing. I've started a new cash account for now and I'll see if I can get this to occur over time in this one. I'll watch for it.