maybe bug in tremolo?

[libero . mureddu3]

Hi!
I think I've found a bug: in this example the first tremolo sign on the B
note is misplaced.
But this happens only with the syntax \repeat "tremolo" etc... while with
the syntax b'4:32 everything is fine. As you can see it happens only with
the B note (I checked A and C.
Libero

{\repeat "tremolo" 8 b'32 b'4:32
\repeat "tremolo" 8 a'32 a'4:32
\repeat "tremolo" 8 c''32 c''4:32}

Lilypond 2.6.0
Mac X 10.3.9
Ibook G4