I don't consider it weird as I knew what Bonnie was doing. I put in the grate to stop her laying (she's a layer) and when I first put it in, she looked at it sideways, as though she were puzzling it out. She could see the bottom of the cage, but she couldn't get there
It was great watching the little wheels turning XD She went up to the corner of the cage nearest me and looked down and to the side again, bobbing her head like it was a perception test, and she shuffled around on top of the grate, both fowards and backwards
She doesn't do it anymore from what I've witnessed, but if she does it and doesn't spot my phone I'll try and get a recording of it. I thought it was weird looking too as it doesn't seem as though a bird should be able to walk backwards but I was watching it
As long as your birds don't hurt themselves and don't show signs of fitting or anything like that, I'd consider it harmless, unless someone wants to correct me here