>was almost as wide as he was tall

That made me laugh real hard even when I am alone reading your story. You're mean to describe Mike that way, ain't you? 😃

Kidding aside, it is a heart warming story.  I heard it several times that grandparents care of their grandchildren more than their children once they have the latter.  Your story proves that.

>my Pa, who spoiled me rotten. 

I noticed the sepia photos and I wondered why.  I thought those would really be great in colored version.  But reading through the end, I now understand.  You are lucky to have caught your grandfather while he is still active. All my grandparents were gone when I was born. 

Good short story there!