I have a similar issue that occurs between V4's figure parts, like shoulders/torso etc. It doesn't always happen with all parts, and not with all skins.. But can happen with skins that normally work fine.

If it's a bug of sort, it'd be nice to know what causes it.  The white lines in Becky's screenshot look very similar to some of the stuff I've been struggling with. (And eventually had to solve in PSP manually, later.)