It depends on how they do it, may be they did return and they simply rented them again, or they may have another way that we are going to fix.
We will keep trying more methods including auto-return without warning for gates that you have more than may be 5, where 1 in 2 are returned. For example ABC Airlines rents 10 gates at X and does not use them, at the month change 5 are returned straight away and 5 are tagged for return next month. But DEC Airlines has 4 gates at X airport too, they do not use them. The 4 gates are tagged for return but none are returned automatically.