Coworkers can be friendly without being your friends. Both are fine.

Warmth at work is real and also bounded. Someone can be great company for eight hours, cover your break, know your coffee order, and still not be a person you would call at midnight. The trouble comes from mixing the categories: expecting friendship loyalty from a shift relationship, or distrusting genuine kindness because it does not go deeper. Both kinds are worth having.

Enjoy the banter without testing it for more than it is. Keep the heavier things for people outside the schedule, at least to start. If one does grow into the other kind, you will know, because it survives one of you leaving.