6to4 and heise.de

[mfritsche@volta:~]$ traceroute6 reauktion.de
traceroute to reauktion.de (2a00:f10:103:201:ba27:ebff:fee3:41e8) from 2002:2e3b:efdd:0:f0d9:85ca:7e1b:423, 30 hops max, 24 byte packets
1  fritz.box (2002:2e3b:efdd:0:9ec7:a6ff:fe8c:cf9a)  101.005 ms  1.755 ms  1.727 ms
2  2002:c058:6301::1 (2002:c058:6301::1)  34.323 ms  30.587 ms  30.397 ms
3  10gigabitethernet6.switch2.fra1.he.net (2001:470:0:150::1)  29.789 ms  39.28 ms  28.729 ms
4  100ge3-1.core1.ams1.he.net (2001:470:0:2d4::1)  38.889 ms  79.088 ms  45.039 ms
5  pcextreme.nikhef.nlsix.net (2001:7f8:13::a504:8635:1)  44.937 ms  38.377 ms  39.988 ms
6  core02.ams05.pcextreme.nl (2a00:f10:170:1::2)  39.895 ms  39.812 ms  39.404 ms
7  mpr2.ams02.pcextreme.nl (2a00:f10:170:14::2)  39.952 ms  61.445 ms  38.151 ms
8  2a00:f10:103:201:ba27:ebff:fee3:41e8 (2a00:f10:103:201:ba27:ebff:fee3:41e8)  40.342 ms  78.759 ms  58.384 ms

vs.

[mfritsche@volta:~]$ traceroute6 heise.de
traceroute to heise.de (2a02:2e0:3fe:1001:302::) from 2002:2e3b:efdd:0:f0d9:85ca:7e1b:423, 30 hops max, 24 byte packets
1 fritz.box (2002:2e3b:efdd:0:9ec7:a6ff:fe8c:cf9a) 2.007 ms 1.889 ms 1.742 ms
2 2002:c058:6301::1 (2002:c058:6301::1) 34.52 ms 29.896 ms 55.845 ms
3 10gigabitethernet6.switch2.fra1.he.net (2001:470:0:150::1) 31.842 ms 37.126 ms 31.995 ms
4 * * *
5 * * *
6 * * *
?