White mark on tooth since i can remember. is this anything to worry about?

Possibly: White marks on teeth are generally from two causes: one, decalcifications where the minerals are being pulled out of the teeth, making them soft, early cavity, see dentist for filling. Two, enamel hyperplasia, something caused enamel to develop odd, like high fluoride, trama or fever when forming, etc. , just looks different but hard, can be covered or left alone.

Most likely NO: Consult your dentist to verify as they will have a history of the lesion for sure. Most of the time it is a hypocalcified area on the tooth, in other words it developed not quite as structurally sound as the tooth around it. There is a product out there called mi paste that can help re-mineralize that area. Whitening will make it whiter so that is not a great solution.