Recently I ran into an acquintence in a coffee shop. Our usual routine is to crack a few light-toned jokes or share some stories (Usually that person is quite a conversationalist and we talk about 5-15 minutes.)
That day the person had a slight facial tic and it seemed to stress them out, and during our conversation it considerably intensified. Seeing that the person was uncomfortable, I cut our conversation a bit shorter than usual.
It seems that for some strange reason people think that a tic makes the situation awkward. I see no reason to treat it differently than a common cold - an inconvenient condition that will probably pass with rest, and if not, then perhaps with medical treatment if needed.
What I am interested is, what is the polite way to communicate in this case with people with whom are on friendly terms but not that close? Acknowledge it and ask if everything is ok? Ignore it? Look somewhere else while talking? Say something like 'relax, comrade, everyone has bad days'?