This is the first time I can recall that I've ever had to fill out captcha on this site. It seems really strange after nearly four years to be asked to prove I'm a human. Does anybody know what might cause this?
I had left my answer open in a tab for a couple of days before updating and submitting. The asker had no reputation.
I wouldn't be able to tell you why it happened but I do know it's a Stack Exchange system that we have no control over. I wouldn't worry about it too much unless it happens multiple times / regularly. It's happened to me once or twice before but not for awhile now.
While you are probably human, even after four years. Your account could still get compromised (hacked login details, malicious browser plugin, etc., etc.). So a regular check for this when the systems of SE detect 'suspicious' behaviour is not really weird. Like @Howdy_McGee♦ already said, don't worry if it happened just once.
