For peace of mind I would or if you know which house it is then let them know. Someone might have tried to steal it, it may only be 30 or 40 quid but that's another fix or meal for someone. Its hard times so expect catalytic conveter theft, fuel syphoning and wheel theft to be on the rise. My dad's work van fleet (Merc Sprinters) have to keep there spare wheels in the loading bay becuase they were getting stolen from under the van. They need special load bearing tyres that are well over 100 quid each think they about 180 or therabouts and one had the cat stolen. The cats are insanely expensive don't know exactly but it was more viable to claim off the insurance than to buy a new one !!