There are 3 different Norton 4k's out there floating around


Made in USA
Made in Mexico
Made in Italy

There were some that came out when production shifted from the US to Mexico that required the 1/8 inch lapping or so to get to a smooth even feeling surface ,

Most of those issues have since been fixed, Lap until the stone is flat and the feel is even so that there are no rough spots left, how long that takes will differ with each Hone

I seriously doubt you did damage to the Chosera, set it on a towel to dry slowly when yer done honing, there are rare days that mine isn't wet for hours...