Apple says it sold a record-breaking 9 million iPhones during the opening weekend the 5S and 5C were on sale.

Gene Munster, analyst at Piper Jaffray, thinks there should be an asterisk on that record.

In an interview with Bloomberg TV, he attributed the eye-popping sales number to "channel fill."

He says Apple sold a lot of iPhone 5Cs to partners who did not sell the 5C to consumers. For instance, AT&T may have bought 10 iPhone 5Cs, but only sold 5 of them. (Those numbers are just for explanatory purposes.)

This is a first for Apple, since in the past it always sold out of all inventory of a new phone. The 5C, while technically a new phone, is basically just an iPhone 5 with a new case on it. Therefore, it didn't sell as well as a brand-new phone.

Munster believes 3.5 million iPhone 5Cs accounted for channel fill and that the real iPhone sales number for Apple was 5.5 million.

(For what it's worth, Munster was predicting 5 million iPhones sold, so his explanation of the real iPhone sales number is a little bit of covering his rear.)

Here's Munster's full explanation in his report from earlier today:

Breaking Down The 9 Million Units. We believe that based on the 9 million number and our observations of weekend sales, the mix may have been around 4 million 5S units and 1.5 million 5C units sold-through (3.5 million sell-in). In our 5-6 million unit sell-through estimate, we had assumed 2.5 million units of the 5S and 3.5 million units of the 5C. The channel fill we are assuming from the 5C was not in our expectations. In terms of 5C channel fill, we note that currently the iPhone 5C is available on the online Apple Store with a 24 hour lead time. We believe this implies that the company has near-full channel inventory of the 5C. Based on the 11 million total iPhones available in channel inventory as of the June quarter, we believe this implies that 5C could be 3-4 million units.

Watch him explain it on Bloomberg here. (We're having trouble with the embed code, so if the the video won't load, head over to Bloomberg):