Porous Rolex Steel?

[ashgate]

i have a 2002 (Y) steel datejust. 36mm. i noticed what seemed to be a deep mark on the case (9/o'clock side) so recently had it very lightly cleaned/polished by a working jeweller to examine the area, it appears to us now that it may well be a small area that the actual steel is Porous, and if fact not a damage. Does anyone know about this? i can't find anything about this happening to rolex cases. The marks would certainly not have been that localised if it is a damage, as elsewhere on the watch there would have been severe damage judging by these marks, and there is no sign of this at all. Is there any record of how rolex behave in these situations, do they admit its porous and replace the case??
see pics attached.