humidity level is ard 49%...bought D80 for less than a month as far as i remember i dont think it should be so noisy when it AF...by the way do you guys' D80 make a sound when it AF?
if any lens make a sound that normally doesn't have, one of the reasons could be that the lubricant in the lens has dried due to the dry cabinet being too dry..
I use a kit lens but the sound when it uses autofocus is almost inaudible. I suggest you bring it to Nikon for servicing since you just bought it less than 1 month.