vertex on the butt always get skinned a bit on all rigify facial bones

[loicbramoulle]

I have this very small issue any time I rigify, kinda easy to cleanup but just in case it's solvable in more systematically:

All facial bones always get a liiittle bit of influence on just this vertex when rigifying.

If not, and for people wanting to clean this up on their rigified CC characters, you can use the smudge brush in weightpaint mode, on the Thigh vertex groups:
DEF-thigh.L
DEF-thigh.L.001
and then Weight menu > normalize all, until it's clean, no more face influence.