position of text in timeSig

[Stefan Thomas]

Dear Lilypond-users,
in the below quoted example the position of the "rit" is ver high.
Does somebody know the reason for this?
Sorry, the example is a bit long.

\version "2.11.49"
\layout{

  \context {                    
    \type "Engraver_group"
       \consists "Text_spanner_engraver"
    \consists "Text_engraver"
    \consists "Dynamic_engraver"
    \consists "Axis_group_engraver"
    \name "TimeSig"
         }
  \context {
\Score \accepts TimeSig} }


%%%%%%%%%%%%%%%%%%%%       the music %%%%%%%%%%%%%%
tempotakt = {
    \mark \default
    s 1*6 \noBreak
    s 1*4 -\markup{\upright "rit."  } \noBreak %tempotakt15-18
 s 8*7 s 8 %tempotakt 19,
\mark \default
\time 2/4 s16-\markup { \column { \upright "subito piu mosso"   \line { "(" \note # "4" #0.75 "= 120)" } \upright "molto rit." } } %tempotakt 20, tempoangabe, hoffentlich schauts gescheit aus
s8. s8. s16  |\noBreak %tempotakt 20
\tempo 4 = 60 s2 | \break %tempotakt 21
                            }

marimba =   {
R 1*6
R 1*5
c' 16 d' e' f' g' a' r 8
R 2
}
\new Score
{ \override Score.Hairpin #'minimum-length = #8
\set Score.skipBars = ##t %damit werden die Mehrtaktpausen korrekt angezeigt
<<
    \set Score.markFormatter = #format-mark-box-letters
    \override Score.VerticalAxisGroup #'remove-first = ##t
    \new TimeSig  { \override Score.TimeSignature #'style = #'( )
   
        \override TimeSig.VerticalAxisGroup #'minimum-Y-extent = #'(-0 . -1) 
    \tempotakt   }
          
   
        \new Staff= "rechts" { 
                \marimba}
   
>>
}