It's way early to say you've got a PCM failure in the works, but it's not out of the question, j. If you have a 5.9 engine with the 56040147A# XXXXX a hot engine stall like what you'd seen isn't at all unusual. If it's the PCM, it's gonna do it again, so you might as well give it every opportunity while you're home and safe. Start the engine and let it idle with the A/C on for a half hour or so with the hood down. Let it get good and hot underhood and see what happens.
Most problems that cause a stall like what you had will leave a code behind and the CHECK ENGINE lamp would be on afterward. But if the PCM takes a short nap, it wakes up with no realization anything ever happened except that it's lost its internal memory... all adaptives and any stored codes will be lost.
So what I'd recommend at this point is to set a code of your own choosing to turn the light on, get the engine to stall and see if the light disappears after the engine wakes back up. It's like putting bait in a trap to see if it's still there after the door shuts.
As much as I hate to say it, your idle problem may be related to what you're seeing now. I see an awful lot of these PCMs with P0505 codes set, which turns out to be an internal IAC circuit failure.
Let me know what you find.