That's about as fine a braille-scale Sherman as you can ask for, Hercmech! The paint and weathering are spot-on! The tracks and the rear hull are really nicely done.
If you sealed your model with any kind of sealer--Dullcoate, perhaps?--pigments will disappear. It's a reaction to the sealant. You should seal your model first--if you like to use sealers--and THEN add pigments and fix them in place using regular mineral spirits, by capillary action. They will darken slightly but stay on more reliably than if you don't use anything.