My 10 month old pup has been cocking his leg since he was 5 months old but has never peed in the house since he became 'clean'.  I can't remember when he became clean in the house but it was definitely before he started cocking his leg.

I am aware he is now in his adolescence phase and until now there has been no dubious behaviour but tonight he was in the living room and cocked his leg all over my other dogs bed.  I shouted at him to distract him and put him back in the kitchen while I cleaned it up but am now wondering if this is just him thinking he is the dogs doo da's now he is getting older and asserting his dominance.

He used to try to pee on my staffy while she was peeing but I stopped this and now he waits until she has stopped and has moved away before marking over her.  Is peeing on her bed just an extension of this?

And more to the point, how do I stop it becoming a habit?

my youngest dog used to pee on the dog bed but luckily stopped when i changed it to blankets instead. they were much easier to wash and get any smell out.
she still will pee on top of where ever my other older bitch toilets in the garden, so i put this down to a dominance thing as she has taken rank over my older bitch.
really i think the think only way to stop this is to keep an eye on your dog and catch it before it happens then rush him outside and re-enforce the good behaviour for toileting outside.also you need to really clean where he's gone in the house as dogs can smell things we can't and will go again in the same place.
by the sounds of it he is making a point that he's in charge but when he feels the pack is in it's right order may feel less inclined to do this but as i said my bitch still does it outside.
don't leave him alone in a room for now and catch him quickly if he tries to pee, you don't want this to become habit forming. he is still young so best to praise him when you get him outside than get angry with him when he goes in the house.  

thanks bear, I have french doors between the kitchen and living room with a stair gate up and the pup is usually in the kitchen as he is too hyper in the living room with my other dog who likes peace and quiet.  My bitch had gone upstairs so the boy was roaming about the living room and clearly wanted it noted that he had been there- the little sod!

As far as I am aware he has never done it in the kitchen but it looks like vigilance is the key.

My Charlie did this only twice I think about the same age, it almost seemed as though he was on automatic pilot and didn't notice he was inside. He also used to wee on my girl while she was mid wee but glad to tell you that he is 16 months now and it has all stopped.
Let him know you are unhappy with this behavior and hopefully it will stop as quickly as it started.
Paula