Thanks for confirming @jwylot, we haven't heard from the OP in a couple of months, so I'm guessing this instance has been resolved.
I don't know how the app checks whether the device is a tablet or not, but if it's checking the device name in the build.prop then it may just be a case that they've updated the lookup table within the app. But with each update they appear to be improving, so fingers-crossed we'll see most 7" tablets fully supported with the functionality expected.
Please use the search feature before posting a problem/bug/idea. What's a Spotify Rock Star, and how do I become one? Using Spotify Since March 10th 2009 Twitter: @mechanimal82