Yeah, I already saw issues with attempting to really package the class as part of the stringification (all sorts of issues, many already mentioned here, both in general and in my particular use); I was just a little surprised not to be warned that I'd neglected to use the package.
I was thinking about adding a new function call to do eval-with-bless-checking, hadn't realized I could actually overload bless to verify the package. I don't do any blessing without packages that I remember in this code, so that might be a clean way to fix that.
At least I've learned something new (didn't realize I could override bless!). I shouldn't be surprised, at this point there's not all that much I can't override in Perl.