VERY light spotting days 20 & 21, what does it mean?

Both mornings when I woke up and went pee as I wiped I noticed a pale pink-ish/brown-ish discharge on the toilet paper. This is abnormal for me. I did not have sex either of these days (or nights before). I didnt notice anything else during the day yesterday (day 20) and I'll keep an eye out today.

Any ideas what this could mean?

No other symptoms have been noticed.