This from Tireman9 rvtiresafety.com blog. Roger is a tire engineer and has some very good tire info regarding tires on our trailers. Check him out.
http://www.rvtiresafety.com/search/label/Cold%20InflationBOTTOM LINE
Tire & wheel manufacturers account for a normal pressure increase as outlined above when they design tires & wheels, so you should not be concerned unless you are seeing a large increase in pressure. If you do see a pressure increase like 25% you need to find out why. Remember you should not be bleeding down your tires when they are hot.