Ottawa traded Lehner and forward David Legwand to Buffalo on Friday for the 21st pick in the 2015 NHL Draft.
"Maybe that's something I have to work on, my maturity level," Lehner said in an interview published by the Ottawa Sun on Saturday. "... I don't know what happened, but I wasn't happy with the way things played out. I think I came out of the gate good every season, I'd play good, and then I didn't get to play anymore. That's something I've got to work on going forward. People have different opinions. I can only speak for myself, but that's my opinion."