Bug

I have a weird bug in my piano app. Sometimes keys (and thus notes) hang. I did a lot of debugging and narrowed it down to what looks like androids inaccuracy of motion event handling:

 DEBUG/(2091): ACTION_DOWN A4
 DEBUG/(2091): KeyDown: A4
 DEBUG/(2091): ACTION_MOVE A4 => A4
 DEBUG/(2091): ACTION_MOVE ignoring
 DEBUG/(2091): ACTION_MOVE A4 => A4
 DEBUG/(2091): ACTION_MOVE ignoring
 DEBUG/(2091): ACTION_MOVE A4 => A4
 DEBUG/(2091): ACTION_MOVE ignoring
 DEBUG/(2091): ACTION_UP B4 //HOW CAN THIS BE????
 DEBUG/(2091): KeyUp: B4
 DEBUG/(2091): Stream is null, can't stop
 DEBUG/(2091): Hanging Note: A4 X=240-287 EventX=292 Y=117-200 EventY=164
 DEBUG/(2091): KeyUp Note:   B4 X=288-335 EventX=292 Y=117-200 EventY=164

Clearly it can be seen here that out of nowhere I suddenly have an ACTION_UP for another note. Shouldn't I definitely get a ACTION_MOVE first?

As shown in the end of the log, it's definitely not an error in region detection, since the ACTION_UP event is clearly in the B4 region.

Logging Implementation details

Every onTouchEvent() call is logged, so the log is accurate.

The relevant pseudo-code for the ACTION_MOVE logging is:

 Key oldKey = Key.get(event.getHistoricalX(), event.getHistoricalY());
 Key newKey = Key.get(event.getX(), event.getY());

Question

Is this normal behaviour for Android (the jumping in coordinates)? Am I missing something?