Why is my chinchilla biting me?

My chin has always playfully nipped, no pain at atll, but recently he has began to bite. He has drawn blood. I feel like he might be angry at me, because I recently started a job and haven't had time or energy to play with him. I do feed him and bathe him regulary though, although I do not give him treats.. He is a very active chin and he hates being cooped up in his cage. I'm not very concerned on if he likes me or not, as long as he is happy and healthy is really all that matters. Please only people who know what they are talking about! Thanks(: