Never. After all, my diagnosticians offered to refund a part of my substantial fee because I had "done so much of the work" for them. So, if I had doubts, it would in part, be about my work, not theirs. Besides, the university clinic had some serious connections to world experts in autism over the decades, and they wouldn't jeopardize it all.
However, the idea that it was so easy to convince them, maybe they just "played along" to humor me has made me wonder sometimes. But, my wondering doesn't rise to the level of a reasonable doubt.
One of my diagnosticians is now a friend and an LGBTQ-autism colleague of mine (where I am expected to be "Exhibit A" at a clinicians' training exchange in December), so she would likely tell me if they simply played along. No, it must be accurate and correct.