A post-sequence is a sequence that is subordinate to and follows another sequence. It remedies some unresolved matter relating to the dominant sequence.
The third through fifth turns of the following exchange are a post-sequence. They resolve some doubt concerning the fulfillment of the sincerity conditions in the first sequence’s acceptance of the request of the first turn:
A: Would you mind dropping this off for me on your way to work?
B: Yeah, I guess so.
A: ’Cause I’m gonna be late getting off because I have to iron something to wear.
B: Well, I will if it’s not too crowded.