subtitle moves notes off staff lines

I've noticed at times lilypond produces notes that are not exactly on or
between the staff lines. I boiled it down to the attached minimum
example, which shows a D flat that looks floated up about half way to E
flat. However, if you comment out the header subtitle, the note lands
precisely on D flat.

Thank you so much for this beautiful music editor! I am enjoying using it
very much. It sure beats dragging, dropping, and flipping through menus.

John
-- 
John F. Gibson
17 Oyster River Rd
Durham NH 03824

\version "2.24.2"

\include "english.ly"

\header{
  title = "How Dark and Dreadful"
  subtitle = "The Rake's Progress"
  composer = "Igor Stravinsky"
}

\new PianoStaff  <<
  \new Staff = "RH" \fixed c {
    \clef bass
    \time  3/2
    \key c \major
    df1.
  }
  \new Staff = "LH" \fixed c, {
    \clef bass
    \time  3/2
    \key c \major
    g1.
  }
>>