Crow „friend“ bit me in finger while feeding - why?

So, for two weeks now there is a crow (or maybe it s two different crows? Idk..) coming to our balcony multiple times a day. When I see her, I come outside with some high quality cat knibble and nuts (walnuts are her least favorite).

In the beginning I put the food and left. Then I approached her/him each day more. Yesterday was the first time she/he ate out of my hand. Today I tried to do it like that again, but she/he seemed more distant and suspicious (why I think it s two different crows coming here). She/he approached slowly, looked, and then bit me in my finger (not too hard, didn’t hurt). I moved and accidentally dropped the food on the railing. She/he picked them up, and left. After picking up the food, she/he instantly left (like always ..).

So I m curious - might there be a reason why this happend today but not yesterday, the first time?

Thanks !