I have an IC35L060AVV207 drive in several customer machines, and have noticed that periodically, I get smartd messages related to attribute 1
(Raw_Read_Error_Rate) changing.  (FYI.  These machines are running the smartsuite version of smartd;) This occurs for a period of time and then the messages seem to stop.  Has anyone else seen this with these drives? 
These are relatively new drives that I see this on, and when I install the latest smartctl and run tests; I get no indication
of a problem with the drives.
Is this indicating a possible drive failure?