Romney's wins are atypical for Republican nominees.
Florida and Nevada are not typical Republican states. It could be argued that New Hampshire is more moderate than the majority of Republican states. However, those are the states that Romney has won in the Republican primaries and caucuses.
After the fact, we learned that Santorum had actually won the Iowa caucus, not Romney, as originally reported. Gingrich beat Romney bad in SC, which is more typical of Republican southern states than is Florida.
The only part of Florida that is like the rest of the Republican south is the panhandle and the northern stretch over to Jacksonville. The rest of the state is made up of many northern transplants, from places like New Hampshire, NJ, NY, PA, OH, MI, etc.
Even his victory in Nevada has to be put into perspective. More than half his votes, according to ABC, were from Mormon voters. ( http://abcnews.go.com/blogs/politics/2012/02/nevadas-a-romney-romp/ )The fact that only 7% of Nevada voters are Mormon only accentuates the small number of people that actually voted. Romney was still unable to get 50% of the vote.
What it shows it that Romney is not the runaway favorite as the Republican establishment wants folks to believe. The Republican Party is deeply divided and Romney has yet to prove that he can win in a "typical" Republican state.