I need advice about my 3 yr old ball python?

i have a 3 yr old ball python, she has always been very docile very much so id allow kids to touch her. i fed her 4 days ago. after i fed her about 30 min later i was going to put her back in her cage, she bit me so i left her there for a while longer. i went to do it again and she hissed so i used a long stick to pick her up, she was ok with that and i put her back. she has been in her hidin since. today i put my hand in to pick her up and she hissed again. so i left her alone and went back like 30 minutes later this time i went to puck her up and she hissed and freaked out. so now im not sure what to do. im always handling her. she loves to go out and i let her roam where she wants to. but now shes in a ball and shes become very aggressive.