are you compinsating for the visual size differances between a 2D image and how they are rendered in the engine surfaces?

of course you will get distortions to a texture when your only looking at an area of 128x128 ish size of a 1024x1024 texture that is now being rendered to a 800x600 or 1024x768 display

engines will interoplate pixels to FILL in as you approach closer than normal resolution size of a texture. Just as the engine will remove every (X) pixel of a texture as it gets rendered far smaller(distant) then its resolution size

so to avoid this, scale your texture smaller then 1x1 original size on your blocks/models or don't let your camera view get so close to the surfaces