Chick with a twitch- Should I be concerned

I have a 3 week old RIR, Rosie, whose neck started twitching about 45 min ago. It almost looks like a nervous tick. She is in the brooder with 12 other chicks of a similar age who seem fine. She is eating chick crumbles normally....she eats alot, and she has not yet been exposed to anything else, food wise. We have seen her drink. I have not added anything to their water either. I am new to this, so I don't know whether to panic, get some vitamins for their water, or just wait it out. Any help or guidance would be greatly appreciated!