Is it because football cognoscenti have been predicting the Denver Broncos' historical seasons since September? Or is it because we are now in an era of offensive firepower that leads us to the supposition that the record will fall again next season?
Manning believes it's the latter.
"I will enjoy it while it lasts. I'm such a fan of the game, a student of the history of the game. So obviously this is a big thing for me," Manning told TheMMQB.com's Peter King on Monday. "But personally, I feel all these passing records are going to fall. [Tom] Brady will probably break this next year.
"And you look at the colleges spreading the field and throwing it all over the place, and you see that style being played in the NFL now, and you're going to see numbers like this happen a lot.
Viewed against his contemporaries, Dan Marino's 1984 record of 48 touchdowns still is the most impressive passing season I've witnessed.
That accomplishment lasted two decades until Manning first bypassed it in 2004. Manning's record lasted just three years until Brady's magical 2007 season. Six years later, Brady's 50 count fell in 15 games.
While Marino's 1984 and Manning's 2004 stand as outliers, Brady's 2007 marks the turning point toward the current pass-heavy era.
Prior to that season, neither Brady nor Drew Brees had ever cleared 30 touchdowns in a season. Since then, Brady reached it three straight years while Brees has done so six times consecutively.
For comparison's sake, a league-average quarterback such as Andy Dalton already has passed for 31 touchdowns this season -- with a game left to play.
It won't be a surprise if Manning's record falls again in 2014. It will be a surprise if Brady -- not Manning -- is the one to accomplish the feat.