My 14 year old Golden will do the same thing. I will let him out in the morning and not every day but enough to where I'm not surprised ..... He'll drop a little every two feet or so about 4 times, sometimes all in one place. He's done the same in the house when we don't let him out early enough.
He eats great and drinks a lot of water, just figured he didn't like to squat that much anymore. He does still go in the yard and will squat some, I just figured it was hard on his back legs to squat and go.