The documentation on Fluent Mocking ends with this statement:

Important

Note that when you use Fluent Asserts only arrangements marked with either MustBeCalled or Occurs will be verified. For other tests you have to use the explicit assert.

What this fails to note is that, while this is true of the function "Assert", there is another function, "AssertAll", which will flag an error if any Arranged function call was not utilized.

On a related note, I left other suggestions for this same page a day or two ago.  I would have liked to leave the above statement using the same feedback utility, but I can no longer find the control that I used to leave those initial suggestions.