PageRank of internal pages consistently higher than home page

PageRank query

[hmpphf]

I have just noticed that our website has a PR5 for the front page and PR6 for all the internal pages. It's not a massive site, probably 25 pages or so and is built using Dreamweaver library items.

I would have expected the home page to have the highest PR because that's where everyone links to, aside from one link from an external site to one of our internal pages.

Are we funnelling our PR around our site in a way that would cause this? Do you think I have anything to worry about? I'm thinking along the lines of have we tripped a filter that would penalise our front page.