Have same issue, has Adobe provided any fix for you?
Few observations from my end is:
1. On a fresh install the title works as expected.
2. On upgraded 6.4 with SP4 [6.4.4], there is flicker on tab title. For a fraction of second I see page title appearing then it goes back to "AEM Editor".
Checking if adobe has provided the fix already, before I raise a Day care ticket.
Please advise, Thanks In Advance.