Thank you for posting your questions here, I will try to answer them to the best of my abilities.
A twitching vein or muscle is not something to be worried about unless it has been going on for a long time or for several days. It is usually something that just stops on its own.
But as I said earlier if it doesnt and keeps going on for a long time, then you should consider an appointment with a either a neurologist
I hope this answered your question.