That's what I was thinking but checking the production figures from this site, it could have been made in December of '71 (the last month of S2 production). Interestingly, the TC started production in September '71! I suppose you could call a December '71 S2 a '72, but most of us think of a '72 Europa as a TC.
Also, Lotus was pretty ambiguous about exactly when a model year started and ended and as John said, it could be considered a '72 if it was sold in '72. Even for current vehicles, the model year's production starts in the previous year so if it were the last half of '71, it could be called a '72.
Never a straight line, eh?