My Mom did the same, but added some yellow mustard too.  Then she scored the ham, so it looked like a harlequin, and put a clove in every square.  We would fight over those. 
And on another note, my friends were discussing how much to tip a Mail Man.  Would you have any insight you would like to share?
I do like mustard on a ham, though I have never tried adding it directly into the glaze. I have a ham for Christmas, and will give that some consideration. 
Mailman tipping.
We like money - though technically, that shouldn't happen. even so, I have never known a mailman to complain   

 - here are the 'official' tipping rules..
No money
nothing valued more than $20
food is perfectly acceptable, as long as its not a complete meal.
Along with verboten cash, my favorite gifts are home made baked goods, and gift cards to coffee shops. Just remember, noting worth any more than $20.
Edited to add: - need to be careful with gifts of alcohol as well - if the mailcarrier brings it onto government property, it can result in termination of employment.