I was woke up after an hours nap and had blurred vision (distance only). About 40 minutes my vision corrected itself. No other symptoms. Concerning?

Probably not. Most likely visual disturbances that were only temporary were likely from just dryness on the eye surface from sleeping with the eyes slightly opened during the nap. Normal blinking corrected the problem gradually. Certainly if the blurry vision returns, however, a visit with an eye doctor would be suggested.