Could he be smoking again?

In October my boyfriend began to smoke quite heavily again. With me being an asthmatic and my sister having bad reactions to the smoke on my clothes, I begged him to stop. 
He told me he would, and seemed to have stopped.
I've just looked in a pocket of his bag, I shouldn't have, but it really smelt of a cigarettes, badly. There is no cigarettes, thankfully, but there is three small mint tins full of butts and ashes. 
Should I confront him? I know there's not much I can do, but he promised me he had stopped. Do you think they're old? Please offer me some advice.