BTW I also regularly realise I'm scowling when I'm concentrating, it doesn't mean I'm angry but I must stop doing it because I'm getting an ugly line down the middle of my forehead! :-)
I had that at a rather large firm of lawyers! They assumed I was unhappy because I was frowning a lot. I wasn't unhappy until my supervisor had a go at me. She didn't like it when I handed in my notice during my probation period (and I told her when I was going to finish too, rather than her telling me to go) and explained that because of the air conditioning being so fierce my eyesight had been seriously affected and (quite strangely in my view) it meant that I was having difficulty hearing what people were saying to me! She even knew that I started with the firm without glasses and ended my 3 months having to wear them all the time. I still have problems, however at least I can see (and hear properly!).
PS the ugly frown is almost gone (after 3 years and lots of different deep wrinkle cream!)
