Okay, I think you guys might be right about the amount of stress the phone is getting. I recorded the accelerometer data, have a look:
(note, the graph's y-axis is on a logarithmic scale)
Acceleration values mean nothing to me. But I can tell you that those green ones are peaking at around
20,000m/s2, and the green is the X axis, and that was the axis perpendicular to the ground (ie every time the phone went up and down). The forward/backward/left/right axes didn't feel anywhere near as much force. Does that mean my phone was experiencing over
2,000 G's of force (1G = 9.8m/s2) every time I hit one of those big bumps? Is that something to worry about?
I'm going to put some foam in between the phone and the handlebar and record some new data for a comparison. Also, I like to say phonefoam.