mower slowly quit driving

I was out mowing the yard when I noticed the rider was slowing down and finally came to a stop. I put it in neutral and slide it back into drive and it started to move slowly and then stopped again. It never got going again. The drive belt feels pretty loose but is all together and on the pulleys. This is a 19 horse power 42 inch cut and automatic transmission thats maybe 2 years old. Does this sound like the drive belt has stretched?

model No. 917.203810