Do I bother chasing it up?

I left a share house over a year ago. One bill was left to be paid (an electricity bill) that had not been recevied before I left. When I left the house the roomates said they would email me about it. I had also been living with my boyfriend for the past six weeks before I left (but my stuff was in the house and the electricity bill is for three months). The roomates and I didn't get along that well and I never heard from them about the bill. At the time I figured if they didnt bother chasing it up with me, why should I with them. But now I realise I prob should have chased it up. They still live together and I am wonder will I sound like a crazy person if I email them about it over a year later? I would like a clean conscious about this!