Shrunk !!!!!!!!

Can U believe it my own carpet has shrunk, but not through cleaning, I live in new bungalow only 12 years old and the carpet is only 4 years old, It's a cheepish 80/20 in my hall,
but has been slowly shrinking on one edge, the edge by the radiator, mmmmmmmm
Does any body else find this happens, after summer months the heating goes on and starts moving carpets, I had three pubs in one month have all there carpet shrink, I thought it was me untill found out they had just had central heating fitted and this is what caused it.
Am I right with my conclusion
Cheers James