I have had this happen after my first laser surgery back in May 2011. I had a tear in my right eye, retina, it was repaired that same day. About a week later I was noticing more flashing and redness again.
I went back the next day after noticing this, and I had another tear in the same eye.
Tomorrow, my left eye's retina has 2 tear's in it, so laser surgery has to be done and I'm not looking forward to it, as you know, it's not pleasant.
Call the Dr's office and make an appointment, tell them what's up, you need that checked out.
Good luck to you.