I really don't agree it was that subtle, but I do agree the response was expected as demonstrated by McClellan and Mehlman being fully prepared to buttress and document (Mehlman's documentation cites many Democrats' statements).
I just think it looks silly for people to be crowing about "he didn't say democrat, he said liberal!". He meant and said liberals and liberal Democrats.
I don't think anyone, including me, would be making the distinction between "liberal" and "Democrat" within Rove's speech if the Democrats didn't put so much effort into denying they are liberals.