Don't have the answer, but I have some questions. Were you running your UC Server Blades and your AWC Server Blades on the same MAS box before the upgrade?
The reason I ask is that MAS 3.0 was the first version to run as a Virtual Machine but only for UC, not for AWC. So I have two MAS 3.0 boxes - one virtual and one physical. One for UC and one for AWC.
In our current environment, upon installing UCA 4.X, the end user is notified of a new Collaboration client, but it's a one time install and you're never prompted again.
So, depending on your previous infrastructure, there might be a place somewhere where an IP address needed to be changed, and was not. Just wondering.
Adam in DC