UPDATE:

to answer a few questions from above;

factory battery (truck built 11/04/2010) lasted until 07/05/2018 at which time it was replaced with a NAPA Legend (last one on my 76 W100 lasted me 10 years)
Cranks, spins fast, so the battery is just fine.

Last week, started normally/just fine. This weekend, Saturday had to cycle the key to get it to pop, but ran fine after that. Sunday morning, did not want to fire. Cranked and cranked but no start. Cycled the key, started for 1 second and died. Tried again, started for 1 second, died.
Cycled the key some more, and she finally fired and ran normally. Then, I made some runs around town and once she was warmed up, started normally.
This morning, called my dealership and explained the problem. They are thinking fuel pump losing it's prime from sitting (2011 Ram with 155,000 miles). They are getting her in next Monday, 2/20 and will do spark plugs, transmission service and check the fuel pressure as well. Max Care Warranty with this one since I bought new, so fuel pump should be covered, plugs aren't but she's due, and one of my key fobs stopped working to boot, so I'll get this all fixed at once.

Thanks for all the replies!

JS