Sticking PC-A or something else?

[TwistedSS]

Towed a friends car down to the beach last week with no issues at all. Unhooked the trailer and drove around a bit. I backed the truck into a parking space and went into the hotel for about an hour. Went to go get dinner and put the truck in drive and it wouldnt move. I let it idle for about 30 minutes the next day and put it in gear and it moved...shifted normally and all seemed fine. Now it is slow to engage any gear from park after the truck is cold. Could this be a sticking solenoid or possibly something else? Tow haul mode light will flash after about ten minutes of driving with the tow haul mode on but it won't go into limp mode or anything. My truck is an 03 Excursion 6.0 with a freshly rebuilt trans (two months ago using Alto Reds and new seals, etc).

Thanks in advance