That's odd, I never had that trouble w. the 2Y I had w. mine. I have a 1100kv medusa now, and it doesn't have any issues either. I have no idea what yours is doing. That's def not normal.
Both of mine were with a futaba 2.4ghz also.
What do you have the timing set to? Did you do the auto tune?
It does sound like some sort or phase sensing issue.