Clients on older version stopped updating after SEPM was upgraded

Can anyone confirm that clients running an older version of SEP 14 should still recieve virus definition updates from the SEPM automatically after an upgrade to SEPM?  Usally I like to perform a staged migration from the older client to the newer client after an update.  After the most recent update clients running 1 version behind have stopped recieving virus definition updates from the SEPM, however they have stayed in contact with the server.  I did upgrade one client to prove my theory, once it was upgraded it started reciving virus definition updates.  Additionally if I run LiveUpdate striaght from the server the virus definitions update on an old client.  Aditionally if I change the LiveUpdate settings policy to only use the default Symantec LiveUpdate server, ie go out to the internet, the clients will recieve the definition updates.