I think it is quite normal to come across this situation. After reading for a long time, you may suffer from eye strain so you need to relax your eyes at this moment. If you feel that your eyes are very dry, you can apply some artificial tears to lubricate your eyes. The muscles in the eyes are used to see things at a fixed distance. It will take some time to readjust the distances. so you don't need to worry about this.
I often feel that my eyes ache when I look at the distance after reading for a long time. I will do some eye exercise at this moment to relax eye muscles. When we stare at the book or something else for a long time, our eyes will get used to this fixed distance. And there are less blinking during reading, so our eyes may suffer from dryness. We need to blink our eyes or apply some artificial tears to lubricate them. And our vision may seem to be blurry when we look at the distance, while this symptom will go away after several minutes because our eyes can adapt to the new distance quickly.
I have mild myopia so I can't see things in the distance clearly. I bought a pair of glasses to help correct my vision problem. But I will take off my glasses when I want to read. You can take off your glasses to read books next time if you also have mild myopia. After reading, I will put on my glasses, so I can see things in the distance clearly.