Bit late as it seems to be answered, but I had a similar problem in a(n admittedly not mac) laptop and it was caused by the case flexing, in my searches for information I'm pretty sure I found some of the older macs had the same problem.
@Khornight2 started
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Bit late as it seems to be answered, but I had a similar problem in a(n admittedly not mac) laptop and it was caused by the case flexing, in my searches for information I'm pretty sure I found some of the older macs had the same problem.