I'm guessing you expected a blended drink, kind of like a coffee milkshake. This is a common confusion, made even more confusing by the fact that other coffee joints have different names for the same thing (since Frappuccino is trademarked).
“Iced” means over ice, aka “on the rocks”.
“Blended” means stuck in a blender, so it comes out like a milkshake.
A lot of people ordering iced mochas actually want an iced blended mocha, aka a Mocha Frappuccino. Good baristas will clear this up at the register.