Is it normal that my pet rat keeps pooing on my bed?

So I have a pet rat named Habibi, I've had her for 6 years now and I have never encountered this type of behavior from her til now. So every time I go to bed, for the past few weeks I've seen little, black, rice shaped objects which look like Habibi's poo. At first I thought they were just some weird chocolate things and I ate one and that's how I found out she was pooing all along. Anyway, she's been doing this every day! And I don't know why! She just won't stop and it's funny because she does it most on my pillows! She's angry at someone and it's certainly me because I am 26 and live alone. Maybe she's angry with me for accidentally pushing her out the window but still. Is this normal? Please help! I really love Habibi (even though she might hate me now)

P.S - I don't put her on my bed, she goes alone while I'm at work

P.P.S - Please don't suggest any utilities I might need to put in my home or anything like that