Stress/no stress

Today rocked.
It truly did.
My Aspie had an appointment with his beloved paediatrician who not only gives him great support and reassurance but today he saw Aspie teen's new anxiety manifestations in constantly clicking his fingers.
I know it's anxiety-driven but I can't figure out if it should be labelled a Tourette's tic or a stim...or even an OCD behaviour as he's sort of able to stop (sometimes) but he's got this overwhelming urge to keep going.
Anyways, the paed saw it and saw that verbal reassurance, coupled with hugs, back rubs and cuddles didn't cut the mustard, either.
It's interesting to note that while Aspie teen denied that he felt any anxiety or worry at the increasing noise of new patients in the waiting room his clicking increased when we walked out there.
I don't know if he's actually able to identify feelings of anxiety or stress as he's lived with them as a constant for so long it's like background noise.
We talked, oh so briefly as he was getting prickly, about stress on the way home and I tried to explain that many people don't realise they're stressed out or anxious until these behaviours appear.
At least I've sown the seed for him to think about and we might be able to discuss it further another day, soon.