Long-time Limbaugh watcher Conor Friedersdorf makes sense of the tactic Rush deployed yesterday:

In order to fully grasp [Rush Limbaugh's] mastery of the strategically ambiguous monologue, let's go back to the line I flagged before: "Last night I was as proud as I have been of the U.S. military in I don't know how long." Earnest praise for the troops? Sure seems like it on first listen. Mocking allusion to Michelle Obama's controversial "proud of my country for the first time" remark? Also plausible! Especially in context. Certainly some of his listeners heard it that way and chuckled. But also totally deniable if necessary! The important thing to realize is that there is no right answer, other than whatever happens to be more convenient for Limbaugh at a particular moment in time.