I have noticed this happening too, more worrying, I had noticed when I drive quite a while, when I look in the rear-view mirror, sometimes the view in the mirror is slightly fuzzy, when I look forward, and back in the rear-view mirror again, the view in the mirror is ok. I asked my ophthalmologist (eye specialist) about it ( my thyroids cause all kinds of problems with the eyes so I was worried tthat this could be another problem starting), and she said that it has nothing to do with the thyroid, but is a natural cause of aging.. The muscles and tissues become less flexible so that it takes a moment for the eye to adjust to the different viewing distances. She says it's absolutely normal and nothing to worry about. The combination of extremely dry eyes and the reduced flexibility make it more noticeable... In my case it means I've not been lubricating those eyes enough. ( and sitting at the sewing machine on my time off, and at the computer at work, doesn't help them very much either )