Hopefully it is just one of those overuse issues that can affect any of our joints. If it is a metal ion issue, you are correct in that it may not show up on x-rays since the affects can often be more in the soft tissue. Like Chuck said, a metal ion blood test would give you a better picture of whether you have a high amount of ions being released, which would be unlikely with a well positioned BHR. If you really feel that you are having problems and want to pursue it, I believe that there was a recent paper published by the Hospital for Special Surgery in New York that presented that neither x-rays nor blood tests were hugely accurate at predicting soft tissue reactions. They were using a type of MRI that they felt was better at giving clear evidence of what was happening in the soft tissue surrounding the joint. Of course the can of worms that this can open is if the MRI does show some soft tissue issues, but the x-rays show that the prosthesis is solid; this could lead to some tough decisions?
I also play a lot of singles tennis during the summer; usually a couple of hours almost every day, and have not had any discomfort other than some occasional IT band issues the first couple of years. I have noticed that my glutes on that side to seem a little shrunken and shallow compared to the other side which gives me some thoughts about soft tissue reactions, but my ion numbers are very low and there is no pain, so I am not going to pursue it.