I have a black string of gum hanging around where I got my pericornitis removed and it was bleeding a lot. Is this normal?

Bleeding. No, bleeding is not normal. Please call the Dentist, Oral Surgeon, or Periodontist who treated your operculum and report your symptoms. He/she may want to see you for a post-surgical reevaluation.
Follow up visit. Your post did not say how long ago you had the procedure, but it might be wise to have your dentist take a look. It might just be a bit of gum tissue.