Obscure lyric placement issue with markups

[Geoff Horton]

I'm getting an odd shift in lyrics placement for lyrics placed above a staff:



music = \relative c'' {
  c4_\markup \small \italic "word" c c c
}

wordsOne = \lyricmode {
  La la la la
}

wordsTwo = \lyricmode {
  Lo lo lo lo
}

\score {
  <<
    \context Lyrics = top { s1 }
    \context Staff = gnotes {
      \context Voice = one \music
    }
    \context Lyrics = top \lyricsto one \wordsOne
    \context Lyrics = bottom \lyricsto one \wordsTwo
  >>
  \layout {
    ragged-right = ##t
    \context {
      \Lyrics
      \override LyricSpace #'minimum-distance = #0.6
    }
  }
}

The first "La" above the staff is shifted so that its center is
aligned with the center of "word", but the lyrics below the staff
don't shift at all. Is this a bug or intended behavior? Is there a
good work-around?

Geoff