Update: Now The Guardian covers.
Earlier: I guess this similarity was noticed some time ago but now bubbling up as a likely lawsuit: '60s rock band Spirit (known for great "Got a Line on You, Babe" and the older bald drummer) claiming Led Zep stole key part of "Stairway to Heaven" from them and want some of the mega-profits. See what you think. They stole a line from you, babe? And here someone does a side-by-side comparison. The Bloomberg story is quite extensive in detailing several other songs Led Zep "borrowed" and later had to settle with authors.