On Vacation and 2007 Service Engine Soon Illuminated

Ok 1st day of vacation...just drove 11 hours with several stops - My Armada ran perfectly. Arrived at the beach, settled in for an couple of hours then drove to dinner. After dinner, I put the key in and she cranked for about 20 seconds without starting. Then again for about 15 seconds. Took the key out and put back in...she started right up (like she always does!). I was VERY relieved until I looked down and saw the Service Engine light has come on! I am 45 mins from an Autozone so haven't got the Code yet. Car seems to run and function normally but I am a little worried about getting stuck somewhere!

Any ideas about what could be wrong? ALL HELP APPRECIATED!! Ill post the code when I get a chance today - assuming it starts!