Reagan Democrats for Hillary?

I just saw this exit poll from Kentucky and I'm struck by the idea more Clinton voters would vote for McCain than Obama.  If true it has to be scary for the Obama side.  OTOH, if these are Reagan Democrats, they probably voted for Bush in 2000 and 2004.  The poll does not suggest how they voted in previous presidential elections.  If Clinton/McCain voters supported Gore in 2000 and Kerry in 2004 then Obama does have a problem.  My guess is these are Reagan Democrats who register as Democrats and vote Democrat in state and local races but tend to support GOP candidates for the White House.  I may be wrong but, for Obama's sake, I hope I'm not.