I had that on my seedlings as well, just let them dry out, a fan will dry them faster. You could make a dilute solution of water and hydrogen peroxide and dab it on with a qtip.

I think it is prolly just the little roots, what type of seeds are they? Covered or Uncovered(with soil)

I'm sorry but seeds that "just sprouted yesterday" wouldn't have been able to develop adventitious roots yet regardless of the type of seed. ;)

Dave

Well...from my experience, I have found that some of my seeds, especially small seeds that are surface sown produce little fuzzy roots hairs once the radical has emerged, or soon after. This all happens pretty quickly, as they are needed to absorb water. All I am trying to say is that the seedlings in question could be just!!!

Good luck with your growing!!!

Here is a link that might be useful: Root hairs on seedling

What kind of plants? Tomatos typically have fine hairs on them and so do peppers - but it doesn't look like "white" fuzz.
I agree with Sarah, I usually see root hairs on my lettuce which is surface sown. But it goes away in a day or two as the root develops. Make sure you're getting enough air flow and that the soil isn't too wet.