It may have to do with the physical location of the BT radio module in the car and thus the coverage to other parts of the car. I've had the exact same experience as Retired above--sometimes I'll leave my phone in my pocket as the driver, and the BT may or may not reconnect, but I've never have that problem with the front seat passenger connection (including when my other half is driving and I'm in the passenger seat). Haven't yet allowed anyone in my backseat to connect to my precious entertainment system. LOL
Seriously though, every single time I get the "cannot reconnect" error message on the screen, I simply have to go into audio sources and select my device already listed as there in the BT connection, and it then starts playing music as expected. It is almost as if the system actually times out too soon and throws up that error, and not that it truly doesn't reconnect.