Luetal Phase Dip?


I had a slow dip starting at 5dpo to 8dpo, which was today. On day 5 and 6 it dropped 2 tenths of a degree so still well above the cover line. Then, yesterday and today, it slowly came back up to where it was before. I don’t think it was implantation (unfortunately) since it was over 4 days and didn’t dip more than a half a degree. Does anyone else have any ideas at what it could be. This is only my second month charting and my fourth month off the pill so I’m not sure what my normal is yet.