People said the exact same thing about the Heat last year when they had a good stretch in the middle of the season.
People said the exact same thing about the Packers when they started the season winning their first 11 or 12 games and looked unbeatable.
People said the exact same thing about the Phillies last year when they were routinely crushing teams night after night.
A season is a very long time. Whoever is in good form in February may not be in good form in June, and that's what pro sports playoffs are about...who is playing the best at that moment. Not to mention, there are some very good NBA teams the Heat will need to figure out how to get past before they can think title (Bulls and Thunder, mainly).