Early Period?

I started my period a week early this month.. or so I hope it’s an early period. I’m typically on time or a few days late. I haven’t really experienced an early period. My periods are usually 35-40 days apart. It came on day 28 (from the start of my last period.)

The first day and a half seemed to have a regular flow (not heavy or light) then the 2nd half of the day going into the 3rd and 4th days were pretty light.. abnormally light for me… to the point I wasn’t sure if it’s a period or spotting. I don’t remember if I saw clots or not.. I was very stressed out the week before.

I am 31 years old. Have one ovary, if it means anything.

Should I be worried about this possibly being implantation bleeding? Is this normal for these kinds of period changes to occur at my age?

I haven’t tested yet, but I plan to test soon.