To add to OP’s answer, this is indeed a “bug” (or, at least, an unexpected feature!) of Linux Libertine. Using the ordinary “full stop” (period) produces the stuttering leader behaviour.
It looks to me as if the “auto” dot-leader in LibO is picking up Linux Libertine’s triple-dot leader which doesn’t get spacing on right or left, thus the “pairs” with one in the middle (if you look closely!).
As illustrated above, it is still possible to use Linux Libertine and get well spaced leaders, but it takes selecting a different leader character. Go to the
Format > Paragraph > Tab > Character menu, and use the
U+2024 single dot leader character = ․ (available from
Insert > Special Character... choose the “General Punctuation” range):
And the character selection: