I realize this was happening to me because I'm resizing the viewport. On one of my controllers init method...
Code:
if (Ext.os.is.Android) {
            window.addEventListener('resize', function () {
                self.resizeFix();
            });
        }
Code:
resizeFix: function () {
        if (this.resizeTimeout) {
            clearTimeout(this.resizeTimeout);
        }
        this.resizeTimeout = setTimeout(function () {
            console.log("aplying resize fix");
            Ext.Viewport.setSize('100%', '100%');
        }, 1000);
    },
I have also seen this bug on a Motorola ET1 running Android 2.3.4. Rezizing the viewport also have consequences on Android 4.0.3 and 4.0.4. When trying to select an input field you have to tap it 2/3 times so you can start writing.
I have also realize that the call to doSizeFix you have added on your 2.2.0 beta 2 sdk introduces the problem of having to tap 2/3 times the input field. This was tested with the kitchen sink