If after removing the seal and flushing the bearing it looks good, hand pack it with grease, and rotate it to fully circulate the new grease. Then if is still feels good, re-install it without the seals, and see how it works. If it works you've dodged a bullet and can ride with it as is. In theory that leaves you more likely to have contamination in the future, but then again the seals didn't help this time either

If you plan on doing lots of rainy, muddy mountain biking, use this old mudders trick from the days before over-priced "sealed" headsets.

Cut two rings about 1" wide or so from an old inner tube. Make sure they're small enough to need stretching to go over the cups. Slide one each over the upper and lower headset cups prior to assembling the fork. Then assemble all as usual, and finish by positioning your new headset skirts over the gap. You might have to put a film of grease on the outside of the inner (usually lower) race so it slips easily within the skirt. Now you'll have both decent mud & water protection and the ability to field strip and service as needed. Unfortunately it won't be beautiful (unless you consider good function a thing of beauty)