Wow. Golf leagues are serious business. I frankly wouldn't have cared so long as you didn't use the 15th club. Leaving the club behind for the round is not reasonable considering that it could be "lost" while you are out playing. I guess they could have forced you to take the putter back to your truck, but even that is kind of a douchey move if the parking is out of the way. It sounds like someone is a little too much into the golf league. It is, after all, serious business.
I definitely wouldn't say anything, other than a possible lighthearted joke. If it isn't a tourney or a money league, who the heck cares? You didn't use the club, so I find what he said to be so petty...a stupid fuss over absolutely nothing. Question though: Did you beat him?