You should be OK; that resistance measurement will drop when the injectors are hot.
I would be concerned if the resistance was low, like 8-10 ohms, which would indicate a partially shorted coil, or very high, like 20-30 ohms or more, indicating a partially open coil.
You can do a functional test with these high impedance injectors by connecting them directly to a 12v battery. Don't hold them open more than a few seconds, however, because they'll quickly overheat without fuel going through them to cool them.
Don't try this functional test with low impedance (< 4 ohms) injectors as you'll fry them immediately. You'll need to put a resistor box in series with low impedance injectors to test them with a car battery.