I used to have grey ash that took a little bit of effort to clean. It used to stick on the glass and I had to scrub it off. Now, all the ash is black. It covers everything. It cleans very easy. I can even vacuum it right off the glass. It vacuums right off everything. I can't blame it on the pellets, using the same for a while now. Any idea if this is good or bad and what would cause it?