Pictures?

Without seeing it, they could all be the same color, just a different batch of production. Usually different batches should be intermingled so that you do not get 'blocks' of one slightly different color.

Some lines of roof shingles deliberately include a subtle variety of colors. Check your shingle manufacturer web site, or call your local roofing supplier!

Some variation is normal, but we can't tell without a picture.

There was one cheapo builder around here a decade or so ago who bought odd lots. You could obviously tell because entire areas of the roof would be off by discernable shades.

Are we talking gray, medium gray, 50% gray, and light gray; or are we talking red, blue, yellow and orange?

It's hard to see but you can see it if you are looking for
it.

let it go. it is 4 shingles on the roof that you have to look for

to see.

which is exactly what most of us were thinking Sophie.

[ahem]

When my new roof was being installed, about 3 rows of shingles about 2-4' long, above each other, (IOW in a block shape) were a different, lighter gray. My roof is plain old Lowe's Estate Gray. These weren't.

They tried to little lady me and tell me they'll blend in over time.

I swelled up like a tick (probably) and told them quietly (deadly quietly) that they needed to be corrected or they could leave my jobsite and I'd figure out how to finish it my own damned self. It was obviously not brain surgery. And of course, I'd have to pay myself and I'm very expensive. If I drove into the driveway and saw it, it's obviously noticeable.

They changed them.

So I'm not going to write off 4 out of 10,000, depending upon where they are and how much contrast there is. Photos would be helpful.

4 is much different than 3 complete rows. I agree, as we've asked several times, for pictures.

replacing shingles isn't brain surgery, but it does take know how

as to how to not ruin shingles surrounding the replaced ones.

roofer can really hork it up if he/she wants to.

thus the advice to let it go.