3 yr Blink and slight turn in head to the left

My 3 yr old son was blinking his eyes while watching TV last year.  We set him up for an eye appt that month and had his eyes checked.  (His 6 yr old sister needed glasses when she was almost 2.  Thinking he may have vision problems as well. The dr. cleared him with good sight).  On two occasions, my husband and I have noticed he will blink and do this eye twitch / tic thing.  We thought he was tired and was fighting sleep the first time.  (We were shopping and we all had a long busy day).  The second time was just this weekend when I was in the dining room and watched him sitting on the couch in the living room him not knowing we could see him.  He would blink funny then his head would turn to the left.  He did it about 5 times.  He didnt blink much, was very interested in the show and didnt do it afterward.  After searching the web this morning I am reading how this may be related to OCD, Terrets, ADHD, etc.  He is sometimes hyper and seems to be a little ADD.  Doesnt want to sit still at times when reading to him, etc.  Can someone provide more detail on this and what I need to look for to know what it can be?  Is this something he may grow out of or is this a sign of something to come (Terrets, etc.)