Survey and Incident closure

Answer:
Getting users' feedback once incident is resolved is not against ITIL principles. Quite contrary, incident should be in status resolved until customer confirms the resolution. Or, as practice has shown, until certain amount of time (e.g. 3 days). I had a project where we use to call user to confirm incident resolution, so surveying users is OK if that's the preferred way. Some tools have that functionality integrated, so you can use that too.

Read the article "Incident resolution and closure: Waiting for the fat lady to sing" https://advisera.com/20000academy/knowledgebase/incident-resolution-closure-waiting-fat-lady-sing/ to learn more.