Should a Centro auto reconnect to a bluetooth speakerphone?

[Spukey]

I have just recently bought my first Centro, and have just yesterday bought a "Beyond BT-BCKC" car sun-visor type bluetooth speakerphone. I have managed to pair them no problem, however I have noticed this...
When I get into my car and turn the bluetooth speakerphone on, the Centro does not automatically reconnect to it. (ie; the bluetooth symbol in the Centro's display does not change to headphone symbol).
I would have thought that the Centro and the speakerphone would automatically reconnect as soon as they were in close proximity of each other.
Because of this the speakerphone times out and switches off.
However, if I make a call on the Centro soon after turning the speakerphone on, it does connects and stays connected until it goes out of range.
Is this problem likely to be an issue with the Centro, or the bluetooth speakerphone.