2016 Sierra 2500 Would not start...

[Offcamber]

Coming home from a camping trip towing my 30 foot Travel Trailer I pulled into a rest area after being on the road for about 4 hours. Truck showed no issues. Parked when in to grab some lunch came out about 30-40 minutes later. Turned the key and nothing. All the lights came on radio played but not so much as a click. Would not turn over. I have two batteries in the truck and both showed full charge. I thought it might be the Park switch so I tried in Neutral and remote start...nothing. I called AAA and right after i hug up the phone I gave it another try....and it started right up. Drove the rest of the way home without shutting it down. Hasn't happen again since but now I am worried it will strand me as I have another trip this weekend. If it happens again its going to the dealer....

 

Any ideas what it could be?

 

Truck is a 6.0L Extended Cab 4x4 with about 23000 miles on it.