Fred,
My JE piston set has the same grooves. They are not optical illusions.
AFAIK, those are anti detonation grooves. As you may also notice, the skirts are coated. LN engineering's website may have some additional info describing the features of the JE pistons they spec in their P&C sets. I believe LN normally sells the pistons with OEM Goetze rings, but there are other options.