According to ESPN Boston's Chris Forsberg, the NBA has created a new uniform rule, prohibiting players from wearing upside down headbands.
Boston Celtics point guard Rajon Rondo is reportedly one of the most famous players who wears his headband upside down, but he did not wear one in the season opener against the Miami Heat.
The NBA made another rule change before the season started, expanding the rules on technical fouls and cracking down on player complaints to the referees about foul calls.
During a preseason game between the Celtics and New York Knicks, four technical fouls were called in 16 seconds, two of which were called on Celtics forward Kevin Garnett.
(Via Ball Don't Lie)