Different brokers have different ways in which they implement buying/selling CDs on their platform.
With Fidelity, if there is already an offer from a dealer attempting to sell the same CD, you are free to enter a limit price that you want to sell at, which could be higher or lower than the existing one(s). You can also set the order as Fill or Kill (which allows it to be live up to 20 minutes to fill or automatically cancel), or good for the day. However, if there is not currently another offer to sell the same CD, you are not given the opportunity to set a limit price - you are submitting a request for bid, which Fidelity allows the dealers on their platform to make bids on, then they will forward you the best of the bids and you can decide to either accept or reject it. Merrill Edge works similarly.
When you were putting together your order, did it say that you were requesting a bid? If it was letting you do this during non-market hours, my guess is that it was - otherwise it should not be letting you get far enough to place the order.
Update: I just went in to my TD account to the CD page, and on the Sell tab it is a template for requesting a bid and so the process is similar to Fidelity discussed above. You submit the bid request, within an hour or two later you will receive notification of the results of the bidding process and depending on the best bid you can decide to either accept and sell, or reject/ignore and keep your CDs.