Have anyone else seen some roads recently turned grey, like this on the map in Stockholm, very strance stuff.
This is only apearing on specific tiles , so I’m guessing it’s part of the postprocess that is done on these.
I think the problem occurs because the images are palletized and sometimes an important colour doesn’t make it onto the pallet.
This tile has had a similar problem for a long time so I’m not sure it’s a recent problem.
http://b.tile.openstreetmap.org/14/8139/5418.png
http://informationfreeway.org/?lat=51.91282276490794&lon=-1.1561158352783747&zoom=14&layers=0000F0B0F
Perhaps the data on your tile has recently changed triggering the problem.
That sounds like the problem yes… It really is a cumbersome problem to solve.