This is strange and not really normal. Do you also have the problem when looking at a print of a image that has the same resolution as the monitor placed at the same distance? Does it change with the distance? Maybe your eyes have trouble focusing at close range.

In VR there is a rather large disconnect between eye convergence and focus distance that doesn't happen in real life. Eyes are converging to something far away but focusing to ~1m. Another common issue is large interpupillary distance and not being in the lenses sweet spot. But if you also have the issue on regular monitors without stereo it might be something else.