I have just installed all new rear LED lights (brake, blinkers, reverse). The lights look great but now the LIGHT indicator on the dash is on. I have not yet installed a resistor so, for now, I am getting HyperFlashing.
I'm not sure if that would be the cause.
Any ideas?

That's indeed the cause. The LEDs pull much less voltage.

LED require less amperage to work, voltage is the same at 12 nominal. The brake lamp sensor and flashers require a minimum wattage (volts x amps) so they do not trip the dash indicator. There is a write up to by pass the relay but do not have it on hand. The other option is to wire resisters to fool the system(by increasing the wattage used of the led bulbs). Just be sure you use large enough resister (ie 50watt or higher) or else you can start an electrical fire.

Thanks guys. Just waiting on the resistor