I didn't encounter it when it was first introduced, I had to log out (I normally don't) and log back in. I was presented with the logon screen and an option check box I'm a human, etc. and clicked logon and it did. No Captcha screen for me.
I shut my system down at night, when I booted and opened my profile page in firefox 39.0 it just opened the page, no logon or captcha screen.