If installed using an offbox database, you may be able to cobble a sql script to grab this info for you.
The below article provides information on the SEP database schema to help you out:
http://www.symantec.com/docs/DOC4324
I reckon the LASTCHECKINTIME db field name in the Inventory Report schema might be handy here, or the DELETED flag under SEM Agent schema perhaps.
Also, you've posted in the Encryption forums. You will get a better response and coverage if you were to put this in the endpoint protection forums instead. You never know, maybe someone already has a script ready to go