Very recently I have noticed a short (1second) squeaking noise when changing gear on hard acceleration like the noise of a belt slipping on a pulley. It does not do it on all gears but mostly when changing from 4 to 5. Other than that the tranny works fine, has always been and is still pretty smooth. Would that be the first sign of a failing tranny? The X has 110k and beside this noise it works like a charm since I replaced the MAF and O2 sensors.