Touch getting stuck sometimes on iPhone 2G

Questions & Answers
1

Sometimes on iPhone 2G one touch gets stuck. It still detected while nothing touches the screen. Until any touch happens again. Happens rare (one time in 3-4 minutes of active touching). No special way to repeat it. Detects with this simple code:

foreach ( Touch touch in Input.touches ) 
    if ( ( touch.phase != TouchPhase.Ended ) && ( touch.phase != TouchPhase.Canceled ) )
        return true;

Log always shows that phase is Stationary and fingerId is 0. Appears on iPhone 2G and 3G. Tested also on iPod Touch 2G, iPad, iPod Touch 4G.

What could it be?

UPD: Appears not only on iPhone 2G but also on iPhone 3G.

2

If you have an adhesive screen protector, it may be interfering with the touch interface, particularly if the home button is cut-out of the protector.