Has anyone noticed a series of small dimple sized dents that run along the top edges of the roof, running from the front to rear windshield?

I have a 04 rx-8 and am quite confused- there is no evidence that it is from rocks, there is no paint chipping and the dents are on such a strange place and pattern on the roof that i have no idea what causes this-

any help would be great-

 

Pics would go a long way here...........

 

hail damage ?