Confirmed the behaviour. Note from my logs LightDM is doing the correct thing and switching to the right VT (only relevant log items shown):
[+24642.17s] DEBUG: User bob authorized
...
[+24642.19s] DEBUG: Greeter requests session ubuntu
[+24642.20s] DEBUG: Switching to existing session for user bob
[+24642.20s] DEBUG: Unlocking display
[+24642.20s] DEBUG: Unlocking ConsoleKit session 30641b34844b43284750e91300000009-1316130205.440319-86078405
[+24642.22s] DEBUG: Activating VT 7
[+24642.22s] DEBUG: Stopping greeter display being switched from
[+24642.22s] DEBUG: Stopping display
...
[+24644.03s] DEBUG: Releasing VT 8
...
[+24644.03s] DEBUG: Display stopped
Confirmed the behaviour. Note from my logs LightDM is doing the correct thing and switching to the right VT (only relevant log items shown): 84750e913000000 09-1316130205. 440319- 86078405
[+24642.17s] DEBUG: User bob authorized
...
[+24642.19s] DEBUG: Greeter requests session ubuntu
[+24642.20s] DEBUG: Switching to existing session for user bob
[+24642.20s] DEBUG: Unlocking display
[+24642.20s] DEBUG: Unlocking ConsoleKit session 30641b34844b432
[+24642.22s] DEBUG: Activating VT 7
[+24642.22s] DEBUG: Stopping greeter display being switched from
[+24642.22s] DEBUG: Stopping display
...
[+24644.03s] DEBUG: Releasing VT 8
...
[+24644.03s] DEBUG: Display stopped