I understand what you are talking about, but have never heard of this occurance on a Subaru. From my research here, this has never happened on a Subaru. I could be wrong though, so help a brother out!
Aside from this, as you might expect, there are a lot of singular events with headers. As this and all my FAQs are a generalization, I cannot go through each peculiarity with each header type/manufacturer, I only report on common occurances.