"...How big was it, and what shape?.."
Hard to tell, it was night time. However, since it was found way up on the side of the mountain, I rule out cow patty (lots of that down in the valley floor, though); in retrospect it may have been coyote.
This was about the time I was scrambling up the rocky trail and almost put my hand on a rattlesnake, so I was a bit rattled, pardon the pun.
"...Glad you had a great time though! I love AZ..."
I love it too; I make it a point to hike/explore the mtns every time I get out there; it is a lot more hilly than Houston!
Rattlers are another reason not to hike at night.
Next time you visit, try the McDowell Mtn Park ‘scenic trail.’