CD keeps playing on 2008 335xi, Logic 7

This is a Logic 7 system (std w/335 series).

When switching from CD to AM/FM for a minute or so, and I go back to the CD,
the song on the track has advanced further into the track as if it has kept
playing on it's own (although I don't hear it because I'm listening to the
radio). If I go to AM/FM for a longer period (like 5-10 min) then come back
to the CD, it has advanced thru several tracks. Again, playing by itself,
as if it did not pause when moving to AM/FM.

Switched back and forth between CD/AM/FM/AUX using the mode button on the
right side of the steering wheel.

Am I correct to assume that the CD should stop where it is when you switch
to AM/FM/AUX, until you come back to CD where it should pick up playing
where it left off?

Possible software glitch?

Thanks,

Mike