Dilated eye exam determined 20/20 vision and no other problems but some floaters. dr. says not to worry. why all of the sudden noticing them?

I will answer: With a question: did you see an ophthalmologist ( and md) or an optometrist ( who usually checks vision and are not doctors.)? If it was an md i would sleep well. If not, go see one. Occasionally floaters are migraine equivalents too but eye pathology has to be excluded first.

Maybe they're new: If your ophthalmologist did a good dilated exam and found nothing worrisome then don't worry.