It's not so much that I'm gleeful when I catch a typo in the New York Times. It's a big paper, it publishes daily, spelling errors are bound to slip through the cracks. But if you are verbally in-the-know enough to be familiar with the verb to grok (a sci-fi neologism coined by author Robert Heinlein to mean something on the order of "comprehending something so intimately that it is a part of you," here used quite aptly in Cintra Wilson's critical shopper review of Comme des Garçons, a label requiring sci-fi verbs if there ever was one) then I would imagine you should realize that its past tense formation is grokked.
It's not as if the Times doesn't know what it's doing. If you double-click on any word in any article you are directed to a definition page, and "grocked" turns up nothing. Grok, meanwhile, is defined as "To understand profoundly through intuition or empathy," and we are given its tense-dependent variants: "grok·ked, grok·king, groks." If you're going to use grok, Times, please attempt to grok it first.