Well, it's an early Michonne page, and we just saw the #19 cover and a couple of #19 pages sell for big bucks, so this page from just two issues later is probably riding the coattails a bit. Plus, Tyreese just had his breakthrough episode on the TV show and looks to play a big role this season, so maybe the timing was just right.
Also, while $1,300 may look expensive relative to historical TWD comps, in the grand scheme of things, there's not a lot of other art I collect that is priced that inexpensively (some, but not a lot). For some collectors, they might not hesitate to pay a couple/few hundred bucks over what longtime TWD OA collectors might deem reasonable, because that's basically a rounding error for a lot of people in this hobby (and, no, I did not buy the page, though I did think about it).
First off, congrats to the seller as well as the buyer. Good price for the seller and this is something the buyer clearly was eager to add to his collection. As you note, an early page with Michonne and Tyrese.
My own thought, though, is that while $1300 may be "inexpensive" relative to other OA, it is not inexpensive relative to WD OA. It's basically 1/6 the price of the #19 first Michonne appearance pages that sold a couple of weeks earlier. Those prices ($8K+) caught people by surprise. But I'd rather have one of those pages than 6-7 of these pages. To me, side-by-side, I view the #19 pages as either undervalued, or this $1300 page as overvalued. I realize there's a big difference between $1300 and $8000, but for those collectors to whom a few hundred dollars is a rounding error, it's probably not as big of a deal.
I'd consider myself a solid collector for WD art, but yeah, I just don't see it. Happy to overpay on even non-splashes, non-zombie pages, etc. I put in a bid late in the game, but realized it was going more than 1K and backed off. Perhaps it actually is the Gene affect post the WD #19 movement from this month.