@ThomasG
Hello, I was facing exact the same issue and found this topic.
In fact even the same number of epochs. After the 40 epochs (and 1 month, it was a big model), the learning rate reached 0 (after the warm-up and linear decay) but the loss seems that can continue to fall.
Let me ask you: Do you restart training using the same learning rate as the first training? You tested other values of learning rate? How they behave? How the changes in learning rate from starting a new training impacted the loss curve? (it continued the same decay of previous training?)
And at the ending of the second training, you loss loss curve keep showing that it can improve further? If so, you trained again?
Thanks in advance.