This is a TEMP error so the command must have been retried and was successful. It's possible to get these if thee is an issue in your fabric somewhere. How often does this message occur? To confirm a fabric based issue, take a look at the error counters on the relevant switch ports between host and array. If the error counts increase over time, you need to rectify that. These type of messages can also occur when local or remote replication control commands are run (SRDF / Timefinder) You can look at correlating the times of the AIX errors with the events in the Symmetrix audit log (symaudit). If it turns out  be related to this activity, they can be safely ignored.
If none of these check out, log an SR and get EMC to check the FA port events for a correlation.

look at the sense data

0A00 2800 04DC 8900 0000 0804 0000 0000 0000 0000 0000 0000 0200 0300 0000 0000

03 Indictate the SCSI Command Timeout which did not complete within the allowed time.

if you don't see many similar continuous errors logged on your disks. You may ignore the error.