> class="cf-captcha-submit"

Yea, looks like its a custom CF page. I got the standard CF captcha screen when going to pastebin. Screenshot and HTML source below.

Screenshot: http://imgur.com/bylyqlM

HTML: http://pastebin.com/6HrfCWFY

It shows up with the HN theme (orange bar at top and beige background) but without other links/text like user info on the right or the footer. I first noticed it the other day when I started using a wired connection at work instead of WiFi.

So it's not even Recaptcha? Sounds interesting.

Yea, its recaptcha. I'll try to get a screenshot the next time it happens.