Bitmap move jitter

Hi Guys,

I made small test with iPad2 and android Sony Xperia Arc. I have a transparent png 200x50px imported to flash. Fps is set to 30. I move this small png 1px to the left every frame. Quite simple, but the result is not that smooth as I would expect. Everything looks fine and smooth, but once in a second I can see some jittering. Looks like it jumps 1px back and forth. On both devices.

My queston is, is this normal? Does anyone have the same issue? Any help will be appreciated.

Many thanks...

Note:

stage.quality = "high" - didn't help

mc.cacheAsBitmap = true - didn't help