HTC One M8 :: Motion Launch Gestures Not Working Properly When Phone Lying On Flat Surface

When trying to use the motion launch gestures while the phone (M8) is lying on a flat surface? I found that the double tap or swiping the phone while it's on a table does not always activate the phone. However, when the phone is in my hand, it works as it should. I'm thinking maybe it's because the phone has a rounded back so when you tap it, the phone will seesaw and it messes with the internal sensor. I never have this problem when the phone is in my hand because the way the phone contours to the hand and making it more stable.