I'm off by $312 on my month-end close today; how did I track down a split vendor bill?

While doing the month-end close today, my AP aging and GL were off by $312. It wasn't a large amount, but I couldn't get it to reconcile. Instead of just plugging it with a journal entry, I investigated layer by layer by vendor, posting date, class code, and credit card feed. I eventually found a vendor bill that had been split into two expenses: one went to a prepaid account, and the other was…