Rehearsal marks change formatting after edit / relayout

Windows 7, GIT commit: 3e51505

Not sure about my description, but here are steps to reproduce on Promenade or any score of your choice created from scratch using defaults:

1) Click any note or rest
2) Ctrl-M
3) Type "A"
4) Hit Esc
5) Double-click the rehearsal mark you just created
6) Hit Esc again

Result: the formatting changes - the box around the A gets tighter.

This actually happens any time the rehearsal mark is re-layed-out, as I saw it first on a mark I hadn't editing. But editing is an easy way to trigger it.

I tried seeing if one of these was the "correct" formatting according to text style, but actually, the text style seems to have an almost random effect on the results.