Minor improper Metal Mixture, imo aka 'streaked planchet' or as kanga said, it's comparable to copper cent 'woodie' streaks.
I agree with kanga and Fred. This seemed to have happened a lot in 1948. Set it aside. You’ll come across more of these. In fact, CRH enthusiasts can probably attest to seeing this quite often.
You should keep that one as it was cheap and it's a fine example of a nickel woodie so to speak. The lines are due to an improper metal mixture.