What Does Presence Of Tissue Piece In Vaginal Discharge Indicate?

I just recently had my period feb 7-11. I have irregular periods occasionally. But here in the past 6 months I ve been having one every months & a half. But Friday the 20th my husband & I had intercourse && I noticed I was bleeding. So I went to the restroom & wiped myself & noticed this chunk of tissue that looked like boneless chicken breast. I sent a pic to my gynecologist & he said it was a decidual cast. Should I be worried?? Does that mean I m pregnant or was??