PVC melts at about 400F, you hedgehog only requires an ambient temp of around 75F.
So as long as your heat source is not pressed right up against the plastic, it wont melt. Space heaters are a safer choice for plastic bins. Heat lamps can be used with bins but you need to take steps to ensure the plastic wont ever come into direct contact with the fixture.
If the air temperature gets hot enough to melt the plastic, it will also be hot enough to cook you and the hedgehog