No, I didn't removed it to upgrade, just booted the CD and ran the fw update.
I will keep monitoring the drive to see how it evolves.
Thanks for your comments
-----BEGIN PGP SIGNED MESSAGE-----
I would worry more about Spin_Retry_Count which changed from 0 to 1
after MX1A. If you removed drive for performing the update it could
be related to a poorly connected cable or some power-supply issue.