Yeah I almost always get the odd calyx in a branch node, and yes, they can bear seed without building up bud mass. You should see my OG kush mother who lives in the closet with my males... she's got a seed at every node, lol, and she's under 24h of light.
Give the green seeds time.
As for how you got odd seeds, you said you pollinated earlier? That pollen might have been viable after all, or you had a bit of residue in your room, or a hermie.