Yeah, people get overly hung up on the monopoly term. Back when antitrust was formed, it was aimed at trust busting. Meaning that several big names of a market would come together and decide how the market would operate, rather than compete.
And i do believe Apple has gotten a slap or two on the wrist for abusing their hold on content distribution. Ebook pricing for instance.
Now, it can be argued that Apple has enough of a vertical stranglehold that anti-trust rules can apply. It doesn't have to be an absolute monopoly to violate anti-trust law.