I believe this reflects the fact that other people who posted may have used photo bucket as their hosting application and hence posted those pics as links. If/when their account goes bad, the viewer gets to see the error message you describe. The error message isn't really contextual and just assumes it is the original owner/user trying to view their photos - hence the confusing language. I have been seeing this quite a bit myself and some of the other posters have made reference to the fact that photo bucket was changing their policies/procedures in ways that had previous users abandoning the platform. When that happens, anyplace they may have uploaded links (like our forum) will likely break.
The good news is that since we can now upload images directly to the site and it handles the hosting for us (through a third party) we shouldn't be as vulnerable to this kind of thing. Unless, of course, something happens to the PNWMAS hosting service (fingers crossed).
So - long story short, it's them not you.
If I messed this up I am sure one of our more savvy users will straighten me out in short order