Many times. One time was during a period when I was still looking to adopt a dog. A very cool looking athletic mutt (likely some AK husky race dog in it) saw me with me with 2 miles to go before my turnaround point on an out and back run on a multi-use trail. It ran perfectly and contentedly at my side. It looked like a possible stray, no collar, so I thought that if it came home with me, I might keep it, but it left me 4 miles later at the same place that it latched onto me.
Once during college I was running at dusk down one of the ridge trails in the Santa Monica mountains and found myself running behind a coyote for several minutes. That was pretty surreal.
Once when I was running just around the neighborhood with my dog, we picked up two or three loose dogs without tags that followed us around. I think I found out that at least two of them were not lost, just loose, but the third might have been a stray. It didn't follow me home, so that's fine.
My gf's dog often found me at random times back when we were just friends and often went running at around the same time (and same trails, we lived two houses apart surrounded by trails), but not together. She would be so pissed that her dog would run off to find me. Later, when her dog would still occasionally run off when we did runs together, and we would split up to look for him. I was always the one to find him for some reason...