This thought entered my head last week during the course of a project. Whilst not true 100% of the time, the meaning is clear.
As a professional, you do a certain job to a certain standard. Your aim is to always meet that minimum professional standard, not only in the *actual* work, but in how you communicate with your clients and customers and the expectations that you must meet. Occasionally (as happened to me last week), something happens that makes you either question your professionalism, or reinstate its fundamental tenets. As a professional, there is not much more you can do than, be professional. Sometimes it's an unenviable circle.
However, in these circumstances, one can't worry. It is futile to do so. For one has carried out one's duties in a professional manner, the results are those that would be obtained by any professional. And there is nothing else to be done.