I Am Fascinated By Human Behavior

There's this lady at my work was nice to me and I enjoyed talking with her. Then she began to turn on me. She told on me for something I wasn't really supposed to do but wasn't anything I got in trouble for. Then she started keeping track of me and what I was doing. It got ridiculous. She actually started reprimanding me. I tried to reason with her, but it didn't really get anywhere. Eventually she stopped I think. I didn't hear about it anyway.
Well now I'm becoming buddies with someone else and she'll try to get my attention for the weirdest things and will say hi to me now that I say hi to my new buddy. I'm like.. what in the world?!
I wonder, is she jealous now because I don't talk to her like I used to? 🤔🤷🏼‍♀️