I've had them in my calves for 10 years now. There came on out of the blue and felt very pronounced and were very visible. I had been going through a prolonged period of stress without realising at the time.
Eventually they calmed down to a point where I hardly notice them any more.

Lately though, they have come back with a vengence. I get them across my mouth, back, chest, practically anywhere, but they are fleeting and random.
The one in my arm was particularly annoying as it lasted for hours. It was gone by the time I went to bed last night and I only noticed a couple of "flutters" through the night.
I tried not to worry too much about it yesterday.Worrying about every little thing feeds my anxiety..

Shortly after my mum died, 14 years ago, I developed an irregular heartbeat and took beta blockers for 18 months. It's gone now thankfully, but it proves my body has a tendency to the twitchy sort of response to stress..