The Storage agent has been upgrade to version 4.0 but the StorageAgentMaster agent is still showing as version 3.0.2.
Is this as expected?
Yes, this is as expected.
The StorageAgentMaster had been replaced by SAMDB agent after version 4.0 so it is not required anymore but it should not be disabled.
There is a known issue in 4.0 (fixed after 4.1.0) that StorageAgentMaster will be still exist after upgrade, but if disabling or removing it the SAMDB will crash. Therefore the StorageAgentMaster should not be disabled/removed.