I have a Regency I2400 that is about 1.5 years old. Yesterday, black “flecks” started coming out of the outlet where the blower expels hot air into the room. The largest of these pieces is about the size of a finger nail. They are black, paper thin, seemingly metallic, and very fragile. They are not pieces of coal. Any ideas on what these are? Anyone else seen this before? Is this something I need to worry about?