mne_flash_bem leading to BEM model inaccuracy

Hi MNE users,

I have come out with a problem with my BEM model, in several subjects,
where the inner_skull mesh is crossing the gray matter's boundaries
(always at the occipital lobe) and therefore I end up losing some dipoles
mne_flash_bem and mne_watershed_bem commands and found an error log file
that says:

MRISreadVertexPosition(orig): could not open file
$SUBJECTS_DIR/$SUBJECT/bem/flash/lh.orig
MRISreadVertexPosition(pial): could not open file
$SUBJECTS_DIR/$SUBJECT/bem/flash/lh.pial

Could this error lead to inappropriate BEM meshes? Has anyone had a
similar problem?

I know I can change the --innershift option in mne_forward_model but since
this problem seems to be repetitive I really want to understand the root
of it.

Any help is highly appreciated,

Thank you,

-- Andr?s