Usually when I see algae streaking, it is darker and more pronounced. Could this have been cleaned in the past possibly and that is why it is more sporadic and the streaks are smaller? Or is something else going on here?
Or just beginning to form? Any chance you know the actual age of the shingles?
I don’t. Best guess is 8-10 years old. This is a north facing part of the roof, where I would usually expect to see algae growth, but it wasn’t shaded at all really. Also had the same streaking on the east facing part of the roof but much less of it.
It looks like someone bleached the roof.
I see this on some roofs around the same age. Maybe the streak guard Warranty is expiring 
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That’s what I am wondering kinda. Usually when I see algae streaking it has a fairly definite start point higher on the roof, like in the image below I stole off Google. These are small streaks that seam to originate at each shingle. It seems like the only way to accomplish this look is to clean what was once moderately worse streaking.
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Well, it does look like it was cleaned with some chemicals. Maybe bleach or some type of cleaner.