Paul, Not sure about Waterlox, but if it happened to me with Tung/Linseed/or Watco I would saturate multiple times with a solvent as soon as possible and then wick it out as much as possible with clean rags or paper towels and flood again and again to thin it down. Angle the piece so none gets on top--It won't totally eliminate it but will help and what it doesn't get will blend in a little.
Most finishes darken end grain a bit anyway, so maybe your choice of final finish depending on how it drys can blend it even more. For the above finishes I'd probably use a fast drying solvent like Naptha or citrus solvent, but look at Waterlox can to find out what they use as solvent. The quicker the better.
Hope it helps or others have better suggestions.
scott P.
2013 Desktop/spindle/VCP 11.5**
Maine