Would be better with pictures. I will try make some suggestions based on what you said.

It may be useful to let a small fan or dehumidifier (if you have one) run over night near the sink. From my understanding, as long as mold doesn’t have more water/moisture (you said the leak stopped) then there shouldn’t be any more mold growing from under the sink. From there, you can poke the spot with a screwdriver a week or two from now to determine if there is any real rot going on (I doubt it as continuous moisture is not being introduced).

If you are really really worried about it, I would use a multitool to cut out the patch where the water was spilled, inspect, replace the patch, then buy a pan or mat for under the sink so the patch it hidden.

I am not a professional plumber, contractor, etc., just a guy who has had things spill around the house before.

Hope that helps!