Fluttering is quiet normal as it's just an involuntary contraction of muscle and it's fades away on its own.Sometimes , it may occur due to stress,poor diet and exercise,too much caffeine ,vit D deficiency or as a side effects of some medicines.
Next Steps
Make sure that muscle twiches u experience in ur arm is not accompanied with any other symptoms
Health Tips
If it doesn't stop,see ur nearby neurologist for proper diagnosis. Do some gentle arm exercises and keep urself hydrated.