I've taken a small stove loads of times in my panniers and never had an issue, think you have to disconnect it which mine does anyway. once took a calor cylinderi in my gas barbie  (diconnected in the van), got searched and the dummy pointed at it and asked "whats that for?" then he 'found' my empty 5 litre petrol can and asked what that was for then started interrogating me as to whether I had any more empty cans 'hidden' (he'd already searched the van) - you would have thought he'd found some semtex. he got told what a dead he was in anglo saxon.