Yeah. It's difficuult because this "thing", this SP, depression, Anxiety, whatever, is our cross to bear, it might always be something we struggle against. Like everyone's life it will be up and down.
I am definately aware of this undercurrent of low anxiety, and I like the way you put it, I've thought about it but never really put it into words. I feel that it is always THERE, it just is stronger or weaker depending on my mental state.
I also get anxious for no aparent reason. I won't be thinking of anything that I can verbally define, but the anxiety is there. It's at that point where I try to distract myself with some activity before it can grow bigger.