Garage has an uncovered interior ceiling which is just old cedar shakes ( there is asphalt shingles over it - about 15 years old). I’ve been noticing a heavy tar/asphalt smell as the weather is warming up while inside the garage. While looking for answers I noticed the “ceiling” has spots like this black one randomly throughout. I only moved in to this spot in April but I don’t recall any leaks while it rained earlier in the year. Any idea what a spot like this could be? Could this be some indicator of the tar smell?