May have flared back up after a period of improvement, or any other number of reasonable explanations. MRI isn't the best study for a bony injury anyway.
In terms of other sports getting MRIs every time a fart smells a bit off - most of it is just overreaction, and it's also to do with the nature of injuries in major sports, tendon and ligament type injuries around major joints. These types of injuries are well-defined by MRI and it makes sense to get one.
MRI in endurance athletes of Seidel's level can be misleading because they will often show inconsequential stress reactions or low level muscle / tendon lesions that aren't symptomatic and are just a byproduct of hard training. Same idea as MRI finding a lot of false positive lesions that turn out to be nothing when used for breast cancer screening.