Hookset

When I picked up my season tickets I was told I could no longer use my folding stadium seats. I would have to purchase a foam cushion or purchase the green plastic seats for this season. My wife wants a seat with a back, so I paid to have the green seats installed. At the smu game people all over the stadium were carrying in and using their folding stadium seats. What gives??? Did they see sucker on my forehead??? Anybody else told they couldn’t use their folding stadium seats?