I notice (all in D mode) that if I WOT from < 5 MPH the car picks up quite nicely all the way through, but there are some rare occasions when I WOT from > 20 MPH (or some cruise speed) and the rev light will suddenly come on, it will stall a bit somewhere pass 6K RPM, and then after a second seems to go into next gear; I assume since the rev meter suddenly drops and picks up again.
Any ideas on this?