My second lab rotation went a little wonky. I chose to rotate in the lab because I had heard the PI speak a few times and was interested, and then found out she was recently funded a large grant. The first month went great and I thought the lab was a serious prospect for me. Then things started to degrade: some of my experiments didn't work, the post-doc I was working under started to really bug me (micromanagement), and one time when I was put on the spot, I fumbled an explanation of my project. However, I put a ton of work into the lab, and then PI read an approved the required rotation report I wrote a the end.
During the final week, feeling like things were a little weird, I asked the PI if we could sit down and debrief from it all. I specifically asked for feedback on what I could have done better. We did sit and talk, but the conversation gravitated towards a broader discussion on what a PhD requires, and I never got any real feedback. She even dismissed some of the technical mistakes I made, and said the doors were open if I wanted to join the lab.
Now, a few weeks later, I check my grades and see that I got a B in the rotation (the lowest grade we are allowed to get). I think it's pretty clear the lab isn't the best fit for me, however I still want feedback. Without it, I feel like the whole system is rather subjective and unaccountable and I will probably always begrudge that.
I'm currently doing my third rotation in a lab I will likely join, however, I want closure (and to preserve the 2nd lab as a backup option). Is it worth asking the PI again for feedback, or should I just let it go?