Source: Ben Rohrbach, WEEI & Ball Don't Lie
It's possible that Ben Rohrbach, an excellent reporter, could be reading too much into Lee's comments, but if he is frustrated with his playing time it's easy to understand why. The former All-Star welcomed a trade to the Boston Celtics under the idea that'd allow him to get a significant increase in playing time, allowing him to rebuild his reputation as he enters free agency next summer. So far, his minutes per game is actually below what he saw with the eventual World Champions.
By his own admission, Lee started off pretty poorly - which partially explains his limited playing time.