Visa1966

Hey all, Opinions appreciated here. 40 days of warranty lefy on 03 SS Bought new in Nov.11 2004. 24,000 miles. going to work this morning and after trans shifted out of first up hill there was nothing there.(Like I was in Neutral) I pulled it into 1st gear manually and the truck started moving again so I put it back into drive and it shifted fine through the rest of the gears again. Just to see if would do it again I pulled over and started again from a stop. Not hard accell, Just normal, and it did it again. Scanned computer at the shop. no codes. I don't get to this board often but I do see lots of trans problem type posts. Tryed to search for this particular problem but found nothing so now i am asking for your ideas. I am a garage owner myself, so i have taken care of any warranty issues myself with this truck. (Don't like others working on my stuff). Never used any warranty from dealer but I am not so sure I wanna pay for the trans problem if its under warranty. Thanks to all in advance...