Got my roof redone in May. Is any of this discoloration anything to worry about?

Sorry for the picture quality and for my total lack of knowledge. Most of my attic doesn’t have a floor, so I can’t get around much up there.

House built in the 1950s. Slats are original, I think. Some of the boards look wet, but there’s no signs of leaks on the ceilings below. Some of the discolored boards also look kind of sappy/sticky, rather than actually wet, while others just look formerly wet. None of the boards that I could reach actually felt wet or rotten, but I can’t reach most of the roof. Should that stuff have been replaced? Or are they just coloring with age?

A few boards have white stuff on them, too, and I want to make sure it’s not mold.

Thanks in advance for any insight y’all can provide.