I agree with Dave, Greys grow up. As they grow our relationship with them must change,as parents relationships change with children.Your grey ,like many others may not wish close physical contact any more.You need to watch his body language to judge what he now finds acceptable and respect his wishes.Never ever punish any bad behaviour just ignoreing it is enough as long as you re enforce good behaviour with verbal praise and reward, eg head scratch,food treat,toy,.Find what reward your grey responds to most and use this to your advantage.If he adores say a wallnut,only give him wallnuts as reward for good behaviour and not as a regular food item. .This in no way means with hold food,but a favourite treat can be saved as a reward.