Unfortunately that looks like the framers turned a blind eye to a crappy cut of wood- that sucker should have been returned to the yard and replaced. I'll bet you 50 bucks it wasn't a very straight piece of lumber that the framers forced into position. Is it twisting yet? I've got a couple roof beams that could make decent propellers, but that's one consequence of a house built in the 70's by off-season ski bums. It was probably installed before having time to dry out completely, and the wood grain is seeking its original alignment as it dries... new construction right? Its probably pressure treated so you shouldn't have much in the way of mold rot problems, but I would double check that with the contractor.

I'm not an engineer, but it doesn't look like an immediate problem, even though the size of those cracks is a little concerning. Interior lumber usually dries out and shrinks completely within the first year or so, but with exterior lumber(facing....West, right? looks like from the photo anyways) exposed to the prevailing weather you are going to get significant moisture into those cracks. Like I said, with treated wood you shouldn't have to worry much about rot, but moisture penetration and expansion/contraction with freeze/thaw I would keep an eye on it at least seasonally...