Paying for Programming already contracted to access

I pay for a channel lineup and many times i access these channels after they had a play date.  Recently, I have found in some cases that when i access them shortly after they have played, I am asked to pay a fee to see the episode.  This has never happened since i began paying for the Comcast Service and wish to know what my agreement is that requires me to pay for something i have already purchased.  Example:  I pay for Starz and missed the Sunday, February 16, episode of OUtlander.  When i tried to access it the next day, MOnday, It was tagged with a fee to be able to access.  I do not remember in the past where something like this happened nor do I recall notification of the any change in program location or fees required.