NASA Stardust: "interstellar" dust?

Did NASA’s Stardust mission really bring back interstellar dust? What is the justification for calling the particles interstellar when the probe stayed well within the solar system. Interplanetary dust would seem to be a better descriptor.

Given that comets can come from who knows where (Oort Cloud, Kuiper Belt, Ceti Alpha System, etc.) and Stardust was aimed at comet tails, it’s entirely possible that it picked up particles from somewhere else.

Plus, any dust that isn’t actually on the sun, including the dust bunnies under my bed, is between the sun and some other star; making it interstellar dust. The stuff on the sun would be intrastellar dust.

From the JPL Stardust home page:

Anyone going to join Stardust@Home and help UC Berkeley find the dust?