Why is my LS temperature needle moves up to 'hot' when engine not that hot???

You've got air in your cooling system. Is the cooling system full? Has anyone done service to the system recently? If you fill the system, run the car and open the bleeder valve, the air will begin to escape as the car warms up. The coolant level will begin to drop and the air will work itself out until there's bubbling cooling coming from the bleeder valve. It'd be advised to begin with the car cold, or at least adequately cool, and keep the heat set to HIGH. I would highly recommend not driving the vehicle until you bleed the system properly. The areas that are not kept cool by direct contact with coolant can be allowed to reach super-high temperatures in an uneven fashion, resulting in, at least, reduced engine longevity. If you're not sure where the bleed valve is, google image search should set you in the right direction. If anything I've described sounds like a mechanic should do it, feel free to ask further questions, or have a mechanic address the issue. Again, really though, don't drive it.