What could explain this odd Facebook friend-list idiosyncrasy?

I recently made a new friend and subsequently added her on facebook. I went to go send some things to her in a message as we talked via text and I found that she and I suddenly weren’t friends anymore, and I could send a friend request again. I asked her about it and she said she didn’t recall deleting me. I looked on Facebook mobile on my phone, and she was still listed as my friend with a viewable profile- not so on my laptop. I cleared my cache on my phone and laptop internet, both, and tried again. She’s still listed as a friend on my mobile browser, but not on my regular internet connection. I’m not offended or anything, but I’m just curious as to what could cause such a bizarre discrepancy.