I am thinking it is. The skin is very in tact and no skin issues in that area and he has also been experimenting with an escape route when out on his FR so I am thinking this may have happened on one of his excursions. But I wanted to post it to see what you guys thought.
Keep an eye on it. Some bruises take a few weeks to go away completely. As long as it doesn't get bigger, spread or have changes to the skin over it then I wouldn't be too worried.