It definitely could be caused by the medication. I had the very same problem for the first 6 months or so after I started my medication. My doctor told me it was probably caused because the med could be causing a vitamin deficiency in my body, so he told me to take a once a day multi-vitamin. Multi-vitamins make me nauseous (don't ask me why-- I think it's the coating on the pills), so I started drinking rich chocolate ovaltine which is loaded with multiple vitamins. If you start taking a multi-vitamin or find some other way to get a bunch of vitamins into your system, the eye twitching should go away. I haven't had it since I started drinking the ovaltine on a regular basis.
If you're already taking a multi-vitamin or getting vitamins into your system another way, you should ask your doctor & he/she should be able to help you.