Why does my gas hob smell so bad?

I have an 11 month old gas hob. (Our landlord replaced it a year ago after the previous one broke, started smoking internally, requiring the fire brigade before it was condemned by a gas engineer and had to be replaced.) I got home yesterday night and husband informed me that the hob was making a funny smell. He's right, it smells very strongly like burnt plastic. Like a plastic chopping board has been set on a flame. There is nothing on the hob. No cleaning fluids, no spills, nothing burnt. By sheer chance, we had a gas man in today to do the annual check on the boiler. Got him to give the hob a check over. All fine, no gas problems anyway. Any ideas as to what might be causing the smell? And what I can do about it? I'm a bit paranoid after last year's issues and worried something like internal wires are burnt..