NO, piston slap is just that the piston tries to twist in the bore and you get it rocking in the bore as the piston passes tdc each time, as they heat up it stops as they expand slightly, the 4wd pistons had a slightly different wrist pin/gudgeon pin offset to counter this, but piston slpa is not harmful in anyway, just annoying!!
The marks on the std cams/pistons can be from a heavily skimmed head or overreving(chipped) and are affectionately known as KISSING marks, but even some unskimmed heads/engines do this, it is so slight though, the crowns(tops) of the pistons are VERY thick so don't present a problem.
tabetha