Ask HN: Google Requires Captchas Just to Search?

Google just asked me to solve a captcha for something I searched for. Like it thought I was a robot for searching "appveyor {build}". (I"m searching for info on appveyor handlebars and what I can put in them.) "Google has detected suspicious network activity from this address" or some such.

I didn't just have to click "I'm not a robot", either, though I don't block cookies. I had to full on pick which pictures weren't pictures of stairs.

Does this happen frequently for some folks? Any way to avoid it? I'm just fascinated that it happened.