Although recurrence of Histo is a possibilty, it sounds like you are experiencing what is called a posterior vitreous detachment. There is a gel inside your eye that breaks up as you age. This causes you to see shadowy floaters and cobwebs. Along with this, many will see flashing of lights (as the gel tugs on the retina) as well. This all will eventually subside without causing any harm to the eye. Of course, it would be prudent to have your eyes checked to make sure the retina is OK (and to make sure that the Histo is not reactivated). This can be done tomorrow.
I hope this helps and thank you.