apostrophe in Fortran cmment causes shift in font emphasis (stron g?)

[Curl, Mac]

An apostrophe in a Fortran comment causes emphasis on  subsequent code to be
incorrect.
I believe it is interpreting chars between apostrophes as a string. Example
( illustrative only)

        INTEGER            ! normal comment
        INTEGER            ! normal comment
        INTEGER            ! Norman's comment
        INTEGER            ! normal comment
        INTEGER            ! normal comment
        INTEGER            ! another of Norman's comments 
        INTEGER            ! normal comment
        INTEGER            ! normal comment
        INTEGER            ! normal comment

GNU a2ps 4.12
using 
     a2ps -Ptssc952  -R --columns=1 -M letter -f10  -j --line-numbers=1
--pretty-print=for77-fixed   <filename>