This just happened a couple of hours ago.
I'm must say I did giggle when I thought of Ivan's SSL Tester being blocked by Ivan's own modsecurity system we run ;-)
It looks like some of the checks use "SSL Labs (https://www.ssllabs.com/)" as a User-Agent - but some don't?
28/Jun/2012:16:36:43 --0400] T@zAWwoBPEEAAH0YajUAAAAI 188.8.131.52 37604 184.108.40.206 443
HEAD / HTTP/1.0
HTTP/1.1 403 Forbidden
Content-Type: text/html; charset=UTF-8