Whilst a password may stop others using the bluetooth connection, you don't say if that bluetooth traffic is encrypted as like wifi, there must be sniffers capable of intercepting that traffic.
Currently I wouldn't have a smart phone as when it comes to security most aren't very smart at all.
Just try a google search for this, bluetooth sniffer and you will be surprised just how many hits you get. I would suggest that you start investigating how to increase the security between your laptop and phone, etc.