In the past we've seen NHL teams restrict access to tickets to outside fan bases during the Stanley Cup Playoffs. However, it's not common practice during the regular season. In fact, it doesn't make much sense to restrict ticket sales during the regular season. Especially for a team that doesn't often sell out.
Apparently, this all came to a boiling point on February 21st after former Sabres captain Ryan O'Reilly scored a hat trick as a member of the Toronto Maple Leafs. Buffalo players were reportedly upset by the number of hats thrown in the ice by fans.