My parakeet has been acting strange lately..?

hi, my bird has been acting strange lately. he keeps going to the corner of the cage and just sitting there. hes 9 years old, WAY past life expectancy for a parakeet. he still eats and drinks and flies around. he allows me to stroke him from his head to his tail, which he's never done before. i would expect he's dieing, him being almost 10 years old. Thanks for your help.