Just read the flight conversation transcript published by The Telegraph (Revealed: the final 54 minutes of communication from MH370 - Telegraph).

At 00:42:62 KL Airport tells MH370 it has entered KL Radar 132.6, to which the co-pilot responds with a "132.6 MH370 copies that", style consistent. Yet when asked by KL Radar to connect with Hu Chi Ming City 120.9 the co-pilot simply responds with "All right good night" - does not copy, inconsistent style with prior exchange. Indication of someone else at this seat?