I updated the firmware on my JTV89, and now when I select an acoustic guitar model and drop 1/2 step down, there seems to be a strange out of tune sound. It's almost like some notes are being produced in standard tuning along with the drop tuning. It only seems to be in the acoustic guitar models. The electric models are fine. I didn't notice this when I was demoing the guitar at the store (with original firmware). I am running a Line6 Spider IV 75 set to a clean amp model with no effects running. Anybody else have this issue? I suppose I could revert back to the previous firmware and see it still has the issue.