Quite a few updates this week.
Plugins:
Akismet v3.1.4
Brute Protect v2.5
Custom Login v3.2.4
Events Manager v5.6.1
Jetpack v3.7.2
TinyMCE Advanced v4.2.5
WP Slimstat v4.1.7
Themes:
Customizr v3.4.9
Flat Responsive v1.2.3
It looks like the Brute Protect plugin has been integrated with Jetpack. This would be the reason for the math challenge question on the login forms. The Brute Protect plugin that handles brute force protection on the login page is failing, so it adds the challenge question. I will test the Jetpack version and try to get that taken care of this week.