I just had this same experience more or less. Yesterday I was going to make Apfelwein until I realized I opened the wrong yeast, I opened my mead yeast instead of the Apflewein...... So I ended up doing a whole lot of brewing yesterday with my girlfriend patiently waiting for me to take her to get ice cream. (Me- Just let me do one brew and we'll go. (40 minutes later) Her- You opened the other yeast on purpose and you know it. Me- .....)
When I did my mead it was a very simple recipe. 12 lbs honey, 4 gallons of spring water, lavlin something or other yeast.
When I took my gravity it was 1.040.... Now, beer calculus had estimated 1.102 OG,, so clearly something was wrong. Then I realized I had taken the sample right off the top and more than likely the honey sank to the bottom. Rather than playing with it and taking more samples I gave it a good stir, sealed it up and decided my next trip to the homebrew store I'd get a wine-stirrer and make sure before my primary firmentation was done that I whipped up the honey sitting on the bottom which probably wont get good contact with the yeast if it's just in a thick layer at the bottom.
My fear is that if I don't stir it well enough then what firments in the primary will be at the gravity I sampled more or less and when I rack it over to the secondary I'll end up having lbs of wasted honey sitting at the bottom of the primary.
Does anybody know if that can happen? or will it just take longer to ferment and the yeast somehow penetrates to the bottom?.