As you can see highlighted in the screen shot above on the left, "When Everyone is a Honor Student" is how the faulty headline was published. The very first entry on page three of The New York Times Manual of Style and Usage says the following:
"Use an before a word beginning with a vowel sound: onion; uncle; honor."It's pretty funny that copy editors published that blunder given that the usage guidelines for words beginning with the aspirate H and the silent H are explicitly spelled out in the style guide's very first entry and even include the word honor. But, it was the morning after New Year's Eve and it's likely several editors and copy editors were nursing mind-crippling hangovers, so a little slack can be cut.
Fortunately, as you can see in the screen shot above on the right, somebody at The Times wasn't totally incapacitated from the previous evening's revelry and was able to catch and correct the error moments after it was published--but not before the Proofreader saw it!
Happy New Year everyone!