mudpuppy -
I have not had a similar situation, but then again the doctor I see is the same one who performed my surgery.
I am just speculating here, but from what you are telling us, it sounds like the doctor is upset that your wife decided to have her AN treated by the docs at House, rather than have him treat it. Right, wrong, or otherwise, he probably feels that if he wasn't "good" enough to treat her AN, why is he now being asked to review her MRI. I'm not saying that this doctor is right or wrong. I'm just giving you my opinion.
Although his behavior is certainly questionable, at least he had the "courtesy" to return your co-pay; another doctor might not have.
If I were in your situation, I'd either a) ask the doctor at House who treated me to look at the MRI; or b) find another doctor in my home town who is willing to review it.
Best of luck,
Jan