4 Month old just started biting why?

[Jay2011]

Hello, my 4 month old has been biting now for about 2 weeks if i go in hes cage he pounces at my finger and does same when hes out the cage i have been told and guessed he is bluffing so if this is the case how long does this biting last? also he does not want human contact when i eventually get him on my finger to bring him out the cage the minute he is out he flys off my finger and then when i go back to him when he is ready to go back in he keeps flying off

any ideas why this is and how to go about it to stop it please

[Jay2011]

Before the biting he was fine with me going in his cage its just now where ever he is he just bites but not so it has pierced my skin yet its just frustrating how my lovely so tame bird has gone to biting i just hope he stops it and it is not a behaviour problem he has grown in to... yea i have tried him in my bedroom where he can not see his cage and he is just the same still biting me also when i get him on my finger he just wants to fly straight off

Thanks for the help aswell