Comfort nursing

Emalline036

So, my son is almost 4 months old now. In the past week, he has started comfort nursing like crazy. It started just being a night thing, and now it's spilling into daytime naps too. We've always offered him pacifiers, but during the past month he has weaned himself and now won't take one at all (I've tried nearly every brand there is).

What say you, ladies? Is this a growth spurt, teething, a bad habit? Will he get over it soon or should I not let him nurse when I know he isn't hungry?