The Celtics return to action tonight in their first preseason game of the year.  And EVERYONE is going to be watching Kevin Garnett out there.  Just remember when you're watching... if he's limping, it's because he's got shin splints and some mysterious calf problem now.“He’s been good, (but yesterday) I thought they bothered him more than the other days,” Rivers said. “So he went through the practice, but I don’t think he moved great. “I just think it’s fr...