Command used: montage -verbose -label '%f' -font Helvetica -pointsize 10 -background '#FFFFFF' -fill 'gray' -geometry 200x200+2+2 -shadow -title '1\n2\n3\n4\n5\n6' kerrerts.jpg montagetitlebug.jpg
Sample:

Tested on: (all 64-bit)
ImageMagick 6.2.8 05/07/12 Q16 (RHEL5)
ImageMagick 6.5.4-7 2012-05-07 Q16 OpenMP (RHEL6)
ImageMagick 6.7.6-3 2012-04-28 Q16 (Cygwin on Win7)
Let me know if you'd like more info.
-Frank