Quiet right Bob well worth a mention now and again to keep people alert, albeit its not only Gas its any fossil fuel and its not only in Caravans this happens all to often in peoples homes as well,
Make sure you have sufficient air for combustion, of your Gas appliances, and Solid Fuel appliances that includes coal fires wood burners oil burners etc. make sure there flues are clear and the ventilation is open and clear.
As in this weather its all to easy to block up those drafty vents DON'T they are normally there for a purpose.
And never bring BBQ's inside