Here's why you're being asked to update your components even though you didn't make any recent changes:
Previously, dragging out a component with a nested instance from the Team Library, would result in the nested instance turning into Frames when used in another file. This meant that when the nested instance in the master component was updated and republished, the instantiation was broken and the instance would not inherit the properties of the updated master component.
Now, shared components with nested instances can be used across team files while preserving the instance; the nested instance will not turn into frames.
We support the ability to swap out a nested instance with another component as long as the component exists in the file locally. You can read more about that under "Swapping nested instances" here.
This new change will allow you to swap out nested instances with shared components as well.
You're being prompted to update so these new changes to components can finish updating.