Perhaps Rush misphrased what the poll is saying, then. Could be that he meant that Mondale had shifted in relation to Coleman by 7. Or could there have been a different internal poll with a wider gap at some point?
I truly have no idea. When campaigns start talking about their internal polls, you only ever hear the good news. So perhaps they had unreleased results that were quite bad for Coleman that have dramatically shifted in the past couple of days, so now it's time to release all the info.
In any case, I do not have a hard time believing Coleman is moving up in the polls. His campaign is really responding well to the Dem's Tuesday night fiasco well, and the Mondale handlers seem to be floundering.