I wouldn't lose too much sleep over it. It's a very minor thing, and I think it was more common with some of the early production models like mine. I've cleaned the keys out, and it's pretty rare now, usually only affecting Shift or the arrow keys. It's just a bit annoying when it happens, because it seems like something that could be very easily fixed in software with only about 5-10 ms of debounce lockout.
If you're having problems with the hardware of a DM42, post about them here.