Hmm.  Silvering out is found in areas of high density, i.e. the dark areas, as these are the ones with most silver in them.  Highlights/pale areas have little or no silver in them, so they don't exhibit silvering out.
I wonder if you have one of the odd proof-type photos that I've seen a couple of times - I have a few, and there was one posted recently for restoration.  They have an odd colour and metallic look to them that is not the same as silvering out, but I don't know what causes the effect.  I think, being proofs, they were not processed very well - perhaps this is the case with your print?