Hi, @brottman -
The Chocolate Maple Porter was the first BBS mix that I ever brewed. It turned out very well, but I am looking forward to trying it again, to see how my skills/techniques have improved.
Regarding your specific question, I really don't have an answer. My only guess (and I could be wrong) is that there is some sort of error either reading or interpreting the hydrometer reading. The BBS mixes are designed to incorporate a minimum of science or twiddling with the knobs, and in my opinion are intended to get one acquainted with some of the fundamental steps as one learns to brew. Having said that, an email to BBS might be able to answer your question, and they should be happy to provide you with OGs and FGs etc. so that you can compare numbers.
Let us know how your beer turns out - I am a big fan of the BBS mixes and recipes, and this one was a clear favourite. If you are able to, I strongly suggest picking up BBS's two recipe books. they are a little expensive on the website, but do go on sale occasionally - or, they can be had for pennies at Amazon.
Good luck!
Ron