Hello,
Absolutely yes.
(In should have understood when you wrote: "So I was having an issue with some of our machines on 12.1 where it was not showing the current sigs in SPC management and causing the big red X. ")
I would please request you to Migrate the SPC (Symantec Protection Center) to the Latest Symantec Endpoint Protection Manager 12.1.
You need to Migrate to the Latest version of Symantec Endpoint Protection Manager 12.1 because the definitions are different for this product version.
To understand check the links below:
For Symantec Endpoint Protection 11.x - Symantec Endpoint Protection 12.0 (32 bit)
http://www.symantec.com/security_response/definitions.jsp?pid=sep11_32
For Symantec Endpoint Protection 12.1
http://www.symantec.com/security_response/definitions.jsp?pid=sep12
For Symantec Endpoint Protection 12.1 RU2
http://www.symantec.com/security_response/definitions.jsp?pid=sep1212
Hope that helps!!