Yamaha DTXpress/DTXplorer/DTXtreme

OK,

you all know how you can mute the drum track when playing to the preset 
tunes right?

well get this, I did a factory reset yesterday,  I forgot the reason why I 
did it, It was a good reason I assure you. and when I went to play along to 
the first preset, (Latin) tune,  The music was muted but the drums were 
there, which was very cool,  I got to play along with just the Latin 
percussion parts, I was so excited to do that, I always wanted to get a 
Latin percussion band going, but could never find the guys to do it, and 
thins was so much fun!!!  however, I thought that there might be something 
wrong so I switched to the utilites screen to tweak the drums back up after 
the reset, and that music mute was gone when I went to play with just the 
drum part, is this a feature of the DTXpress, or was it just a "Glitch In 
the Matrix"

Herb