new dishwasher / stored in in cold garage

All the ones I have installed always have some water in thier pump

I've never noticed it (but then, I've only had about 2 or three new ones, ever)...

If OP is worried, he could always drop the hoses to the pump...

will this little big of water (that will be ice) ruin the pump?

All dishwashers and washing machines are going to have a small amount of water left in them from the factory. Not enough that freezing will hurt them because many dealers warehouses and no delivery trucks are heated anyway. Just wait sufficient time after install to let the water thaw before turning on the machine so the pump isn't trying to turn while froze up.

I'd say it would be highly unlikely unless there's a trapped area somewhere in a plastic pump housing, but even then I'd expect enough bypass to avoid a problem.

If, as someone else says, the manufacturers are shipping them w/ some residual water, they certainly aren't always being kept in heated areas before delivery...