I would say it was because of the throw of the roror to the left loading material under the left side chain and stretching it. I had a 2366 and it did this too. since traded up to an 03 2388 and I am rapt.
SMIlEY IS RIGHT . IF YOU WANT TO GET MORE lIFE FROM YOUR CHAINS CHANGE THEM FROM SIDE TO SIDE EVERY ONCE AND AWHIlE. THIS WAY THE CHAINS WIll STRETCH MORE EVENlY.