As several reported, some of the existing heads were changed in the hak update. This was mainly done because the some of the heads were originally oversized or anatomically incorrect, but it was done in bulk operation so it's to expected that some didn't come out right.
Please consider though that while they may seem wrong to you at first glance, that could also because they are simply somewhat different compared to what you are used to. Generally, they've been adjusted to match the size of all other NWN heads.
If you still feel that a head type is looking wrong, please post a screenshot of it in this topic and we will get it fixed asap.