[atlas] ipv6 ping to root name servers failing?

Hello, I noticed a few days ago from the built-in probe graphs that ipv6 pings started to fail to the a-root name server instance serving the probe I host. Now also the j-root serving the probe is dropping pings. Some other instances of the same root servers at the moment are still answering pings. If it is intentional that root name servers are starting to drop pings, something should probably be done to the built-in probe measurements/graphs. Does someone know more about this, will all roots be dropping pings in the future or is this just a Verisign thing (a and j operator)? Tapio