Did I overwash?

Yesterday I made 2 identical lith prints on Fotospeed lith paper. One of these I toned to completion in goldtoner. This morning I found that the white border on the toned version is slightly less bright compared to untoned one. I'am quite certain I did fix them both equally long. The only difference I can think of is that the toned one has been washed longer. Could any of you comment on this? Is it likely that extended washing can be the cause of this?

Thanks

It is possible to wash out the optical brighteners in the paper. How long did you wash each print?

The untoned one a little more then 1 hour, the toned one in excess of 2 houres..

Two hours is too long a wash. Did you use a wash aid? Follow the manufacturers's directions. Washing for too long can actually decrease a print's archival permanence.