Was this my period returning?

I'm 3 months postpartum and exclusively breastfeeding. On Tuesday I noticed a small amount of blood when I wiped and figured I was just getting my period back. I bled very lightly through the night, but by Wednesday night it seemed like it had stopped. I kept a tampon in just in case, but this morning there was almost nothing on it, just a small spot of brown/red. Before pregnancy my periods were very heavy the first few days and lasted more than 2 days. Was this my period or spotting for some other reason?