Yes, there is an option called "Minimum Length of a Call Answering Message" under Messaging->Messaging Management through CallPilot manager. If this setting is too high then a quick message, (Hi,it's John. Call me.), may be lost. Using the Session Trace tool on the server will show you this error.
The default is 500 ms but appears to get set to 3500 ms on migrations and some upgrades from previous release.
Good Luck,
Barnie