Janet, I have had Nilah since she was a baby. When anyone tells her to step up, she will appear to bite your finger, and most people yell, "shes trying to bite me", but in actuality, she is checking to see if your hand is stable enough for her to step on. She only does this sometimes to me, it's rare when she does. However, she will occasionally just out of the blue, she will give me a somewhat light bite just for no apparent reason, I think she's just reminding me that she can, if she wanted to....
Bit at nighttime, when she wants to go to bed, SHE insists on the same ritual......she quietly says, " do you want to go to bed." over and over, and she has a spot she goes to in the same room as her cage, (it's the top of the curtain rod) and she waits patiently. When I get up to go get her to put her in her came for bed, she I sits on head rubs and scratches,while she whines in a quiet voice, for what seems like forever.....I have to stand on the top of the love seat or table to do this. As my arm gets tired, I tell her time for bed and to step up, she fights me on stepping up, sometimes sternly letting me know by biting me hard, but not too hard, and when I finally get her to step up, as I'm climbing down, she always has to get in one HURTFUL bite, then she happily goes into her cage and says "nigh nites"!
But I know what you mean, it's almost like they have an urge to bite down on you, but they don't do it hard.....they just have to get it out! There are times during the day, that might happen.
My hands feel like hamburger some nights, no bleeding, but a strong bite none the less....