Why does my roomba leave dog hair along the edge of the rug when it mo

When my roomba goes from my rug to the smooth floor it seems to be depositing dog hair it has picked up from the rug on the hardwood floor along the edge of the rug. This has just started this past month. I replaced the main brush bar, filter, and flexible bar with no effect. I hope someone can give me an idea of what to try next.