I was on a UAX flight in Sept/Oct (ORD to YUL if memory serves me right) where there were only 12-15 passengers on the plane. For some reason, they decided to do no gate checking of rollerboards. Passengers were instructed to put the rollerboards in empty rows on the floor. I sat in a row on the two seat side of the ERJ with an empty seat next to me. My rollerboard was in the empty row in front of mine.