FWIW it wasn't pay walled here. I just had to press "Show full article" and could read on. Perhaps it's based on geo location (I'm not their market) or how much one's read them lately?
Edit: if it doesn't work try again in a private/incognito tab to make sure it's all fresh cookies
So depending on the http-origin header the article is paywalled or not.
This is a trick I always use, it works for many newspapers.
It's not a big deal, I can use the archive link or just not read it, all those articles are merely of the "mildly interesting" category anyway. Not to mention that they are 90+% fluff and the core message could usually be summarized with a few sentences.
I am curious though, given that this is HN, does anyone know how they are doing that paywall tracking these days? It is not just NYT where the fresh incognito window no longer works to get around the restriction. Washington Post too, for example, at least for me.