I've had this happen to me two or three. On all occasions it was during a hard left hand turn, that I upshifted during the turn.
In both cases, as I've powered out of the corner, it's popped out of second and "BANG" revs go up.
Second is a tad nochy, if you don't pull all the way back it tends to catch on the first notch.
I'm now shifting a bit more "spirited" and haven't seen this for months.