Anyone have seeds in FF?

I am using a FF Ocean Forrest, FF Light warrior, perlite, and worm castings. I've been growing these plants for 9 days and suddenly this little red plant started to pop up right next to my plant. Wondering if anyone else has had something like this?

I'm using almost the same mix, and to answer your question, no. My guess is maybe a seed got in during the planting. The compost they use to make these soils is pretty well fermented during the composting process. It's unlikely a seed would have survived that process. But I guess it's not impossible. Remove the red plant. If more red plants pop up, repot or remove that pot.

I'm not using worm castings in my mix, so MsBBB's answer is the one you should go with.

I had a problem with clovers growing in my outdoor tomato pots with FF
But I'm sure that was because of the clovers in the grass on the side of our property