Can anxiety and stress cause twitching just in my bicep. it is a fasciculation not a fibrillation. could it be anything more serious?

Of course: Anxiety symptoms are not a sign of illness, they are the mind's ability to produce the "flight or fight" response which gives rise to many physiological changes include body pains, parasthesia, dry mouth, aphasia, tremor and sweating. Depending on the cause of your anxiety symptoms, your health care provider can recommend appropriate treatment.