What Could Cause A Visible Purple Vein Like Appearance On The Inside Of The Lower Lip Which Feels Strange?

Hello. Yesterday I felt this slight bulge on the inside of my lower lip (felt this with my tongue). I pulled my lower lip forward and saw a slightly purple vein perhaps 1/2 . It does not hurt, but wondered if this is something normal? Will it go away? Why did it appear? It does not bother me to eat. Actually, you wouldn t even know it was there except I could feel it.