I am sorry I didn't get back to you about that barkless! I can't really see much…if it is just on one side, it could be a muscle knot? One time Querk had a dip like that on his thigh, and within a few days it went away. I really think if it was hip related that you would see him acting in pain, before you would see a physical change in his structure.
I think if he was my dog, I wouldn't even worry about it until he started acting like it hurt. Because, even if it is hip dysplasia, there isn't a thing you can do about it except for adding some food supplements once he starts having some pain.
Now if he is limping, or hopping..it might we worth it to do the xrays...but if not, I would just wait and see....hope that helps some...