Centering markup on note

[Nick Payne]

\version "2.13.7"

\relative c' {
   \override NoteHead #'style = #'harmonic-mixed
   <d\4>4_\markup \column { \upright\teeny { 12 } \dynamic p }
   <d\4>4_\markup \column { \center-align \upright\teeny { 12 } 
\dynamic p }
}

In the above, I can't figure out how to get the "12" vertically aligned 
with the other elements (string number, note, and dynamic marking). It's 
slightly to the right and using center-align puts it too far to the left.

Nick