I get regular cleanings every 6 mos & have an overall healthy mouth/teeth. noticed a dark vein on my gum line that wasn't there before. normal?

Dark vein?: Only a visual and clinical exam can determine what this is. Make an appointment to see your dentist.

Anything: Anything that "wasn't there before" should be immediately evaluated. The term "dark vein" is not of and by itself diagnostic. Please be evaluated by a Dentist or Oral Surgeon.

Tattoo?: I agree that the only way to be certain is to get an exam but often it is more a matter of sudden awareness rather than sudden appearance. Silver amalgam can cause tattooing in the gum tissue or it could be a varicosity. Have the dentist check it out.

See your dentist: Any new gum pigmentation that does not resolve itself in two-three weeks should be evaluated by your dentist.