I'm with Bart, not sure if it's a BFS thing, but I get them. I seem to get them more often when my nervous system is on high alert or muscles are tense (i.e., when worrying about other neurological issues) which makes more a nice combination. I just got one now typing this, my first in days. Ha. These are one thing I've learned not to worry about...now if I could convince myself about others...A