You're the perfect consumer for Apple... blindly following. Of course there's excess inventory, why would Apple try to move more iPhone 5s's. You do not understand economics.
Actually he's intelligent. Why would Apple have excess inventory following the quarter where they sold the most iPhones in any non-holiday quarter ever? If you've followed Apple at all, you'd know that Tim Cooks greatest accomplishment as COO was streamlining Apple's supply chain significantly, which helped lead Apple towards the record profits it generated. Most Apple products you buy have been produced in a factory that same month. They don't keep warehouses full of unsold products like some other companies, and even if they did, the warehouses would be empty after a record quarter.
No, Apple does not have an excess supplies of iPhones. What they have right now is excess production capability. They are currently in a period where peak demand for the current iPhone is dying down, but the factories are not yet producing new iPhones for the next iPhone launch. Any additional iPhones they sell now can also be produced at the lowest cost possible, because demand on the factories is low right now. Thus the promotion.