What Causes Involuntary Nervous Eye Twitching In A Child?

My 8 year old grandson has been having a lot of like, nervous(not sure if describing right) eye twitching without realizing that he is doing it. He was at our house for about 20 hours on Fri and Sat. and I noticed that his eyes would like shift from right to left and he would raise his eyebrows and when I asked him why he was doing it he said he didn t realize he was. This happened more than half the time he was here and I didn t always say anything but, he kept doing it. He is a very smart little guy and is active and not a bouncy/all over kind of kid . Is it possible he is having early symptoms of something serious like seizures. He has no serious injuries that we are aware of. I guess what I meant was like Banging his head while playing or anything. I was also wondering if this could be a sign of migraines that my daughter and I suffer from. Thanks so much.