Why does my 6600m unexpectedly and unwantedly change antennas on a band change?

kg5udale .

I'm a relatively new 6600m user and mayhave missed something in the massive reading I've had to do to just get the thing on the air. When I am on one band (e.g. 40m) on Slice 1 using Ant1/Ant1 and on 20m on Slice 2 using Ant2/Ant2 and then open slice 2 to change bands to 80m, the antennas in slice 2 frequently change to Ant2/Ant1 or Ant1/Ant1. It happens frequently enough that I am concerned about trashing the transmitter or receiver transmitting on the new band on the other band slices antenna. I can't find any mention of this happening in the user guide. 

Is this a fault that I need to send the radio back for repair? I can't imagine this would be a feature of any kind.

I've gone key down a few times now after a band change and not paying close attention to the ANT/ANT in the new band. I'm very concerned.

Can anyone advise, please?

73,
dale, kg5u

Alan

K9SO