we've just had a porcelain patio laid, approx 60m2, it was laid 4 weeks ago.

Been out today to give it a spray over with the garden hose and a sweep and noticed around a lot of the pavers, it looks as though the top colour/coating (I know that arent painted or coated but the only way to describe it) is wearing off or coming away? There no evidence of a residue but its on most of the pavers, even the few that havent been grouted yet. At first i thought it may of been grout residue but its not.

Any ideas please before I call the supplier? Just wondered if anyone had ever seen it before?