I have had the fluttering sensation before. As a matter of fact just last night I had it will on the computer. It didn't phase me one bit. I have had them for years and I have just gotten used to them. I don't think that they happen to often anymore and if they do I don't notice them. Somewhere along the line I realized that it was an anxiety thing and just let it go. I used to get really afraid of it though. Somewhere along the line I realized that it can't hurt me and means nothing so I let it go.