...and unfortunately it'll really cost your more money and more hassle. 

It's hard to see the pine-needle build up but it occurs and unfortunately it cause water/moisture to work it's way down. 

In this case it started a small leak in the master closet.

As you can see the damage was pretty severe considering pine needles. Maybe a big branch could've caused the problem but there were two separate places on the roof with the same issue. 

We had to replace a lot of OSB sheathing, 

Here's the second spot we identified. 

We installed new OSB sheathing, new felt paper and added a granular surfaced roof leak barrier in the valley. 

Here's an entire section replaced with architectural shingles.