whine in tranny when shifting

[chinaman]

ok, so I get the slightest whine when shifting from second to third. It is very faint, I can barely hear it and it only lasts a split second right before the shift, unless I am towing then the time it take to approach the appropriate rpm is a touch longer so the whine is a little longer too.

everything on the DD appears normal relating to the tranny at this time

Thanks