What firmware are you running? Does it do it in flight? Testing indoors props off is not going to be indicative as the aircraft is trying to change height and direction and getting no feedback from its sensors. If it does does it in flight consistently then I'd do a full IMU calibration with the Assistant and see what that does. Then update to the latest firmware if you haven't and see what happens. If there's still no joy then it's probably time to talk to the dealer about a warranty return.
I have very occasionally had this in flight - the aircraft almost hiccups. It's as if there's a very brief opposite stick input, then it all goes fine. I haven't seen/heard it happen in flight more than about 3 times in 7 months, though - and it was always during high speed manoeuvres and I could never replicate it consistently. It therefore became "one of those things".