Thanks, Cap. Pillowing is the rounded edges of raised tiles. These tiles had been laid at slightly varying angles, resulting in some edges being higher than their neighbors. That is "lipping." Some of these were actually bad enough to be tripping hazards.
Honing them down does not level the whole tile, it only averages the edges so the lipping is eliminated. Because of the high gloss, you can see how it breaks up a reflection, something that was not as apparent before.
Now if you pull in on the edges of the tiles, you'll see that lots of them appear to be slightly rounded. That is "pillowing."