For months there have been rumblings that the major record companies were unhappy with the Net’s premier music download store, and at least one label was going to seek a major change in terms when its current contract with iTunes expired this year.

As it turns out, that time is now and the label is Universal Music Group.

The label’s iTunes contract expired at the beginning of June, and so far the label has refused to ink a new one-year deal. Instead, the label wants a month-by-month agreement with Apple. Although the label’s change of attitude toward iTunes doesn’t mean Universal will pull its tracks from the online music store, it does mean the label wants more control as to how its music is sold online.

According to insiders, a major sticking point is Apple’s insistence that the label provide iTunes with any track the record company might be pushing on another online music outlet. By switching to a month-by-month agreement, Universal is free to make iTunes wait its turn by giving another outlet an exclusive on any particular song or album.

A month-by-month deal is not exactly a new concept for Universal. The label has similar deals with Yahoo, Best Buy and Wal-Mart.

If the world’s biggest record label lands a month-by-month with iTunes, other labels are sure to follow. ITunes’ initial strategy of pricing individual tracks at 99 cents per track and single albums for $9.99 each meant each label had to agree to pretty much the same deal. But that was during iTunes’ early days. Now that the online music store is the third-largest music retailer in the country, the labels are having plenty of second thoughts about how Steve Jobs should sell their music.

But don’t expect Universal to go for a deal similar to the recent iTunes / EMI agreement, which so far has been the only exception to the 99 cent-per-track rule. Under that agreement iTunes sells unprotected EMI tracks for $1.29 each.

Universal has made no indication that it might be willing to shed digital rights management protection for a slightly higher price tag. Instead, the label has expressed a desire for Apple to license its proprietary DRM so non-iPod personal players can play songs purchased from iTunes.

This isn’t the first time the labels have tried to change their agreements with iTunes. As they renegotiated their yearly contracts with iTunes last year, there was much talk about the record companies wanting more control over online sales, including the ability to decide pricing on a track-by-track basis. But Apple refused, and iTunes’ 99 cent blanket priced remained intact for yet another year.

“Apple has had a preeminent position against the labels for some time,” said Enderle Group Group principal analyst Rob Enderle. “It was only a matter of time before the labels tried to exert control.”