Hey....I have noticed Oscar my has developed a habit of chewing on his feet. He doesnt hurt his feet but seems he is preoccupied of late with chewing at them. When handling Oscar I will have him laying on my hand and can inspect his feet whenever I want....no damage but just curious what can lead to this, or is it simply a habit that will persist or diminish in time?
Sometimes animals (including birds) will chew/lick an area that is irritating/itching them or causing them pain so probably the first thing I would do is see a vet with him to be sure theres nothing like mild arthritis hurting him. It also may be a behavioural thing, in which case you may want to deal with it in a similar way to a plucking bird to prevent him getting worse and hopefully stop him doing it excessively as the area will get sore eventually. Try to pay no attention when he does it as you don't want to accidently reinforce the behaviour.
One last thing, how long have you had him and how old is he? It may sound silly but Ollie didn't start preening himself properly until after the first few weeks we had him. Could it be something like that your picking up on?