Yes, they can go through age but, if fitted correctly (clean surfaces, sealer in the correct places, tightened to correct torque) can last the life of the engine, especially if the breathers are clear. 

If they have been replaced with non VX ones, their life span can be a handfull of months, sometimes a lot less.

Thanks for you are replies, yeah i checked the breather box and they were ok, the lil pin size one was clear aswell, im not sure if the leak was cause by the guy who sold it to me had steam cleaned the engine. Hopefully nothing else will go wrong, especially electrical wise, but touch wood, everything else has been ok.