DirectAccess - IPHTTPS Tunnel with native IPv6 client

I observed that in a DirectAccess KerbProxy scenario, a Windows 8.1 DirectAccess client with native IPv6 Internet connectivity is still using the IP-HTTPS transition technology for connecting to a Windows 2012R2 DirectAccess server also with native IPv6 Internet connectivity.

Is this normal behavior, even when native IPv6 Internet connectivity is available?

Note 1: the use of the IP-HTTPS transition technology is confirmed with a Wireshark/NetMon trace.

Note 2: see also the related thread http://social.technet.microsoft.com/Forums/en-US/e4bbb30e-161a-4847-918d-ba34934b4877/directaccess-double-dns-registration-issue-with-native-ipv6-client?forum=winserverNIS

Regards,
Stefaan