Heating aircraft on the ground
 

I was boarding a plane at Singapore earlier this month and noted that the heater elements at seat level were on making it rather warm - although the air con was also on fighting against the heaters. Ground heat is very welcome at Anchorage or Moscow but not really necessary at SIN. I complained to the cabin crew who correctly said that things would improve, which they did. My question is, would it have been an error by ground staff, an engineering test or some other reason?

Option 3 most likely......