It is true that from time to time, people are reporting that autoresize does not work for their canvas apps. It is in fact good to see that Facebook admit that they cannot solve the all case, especially when the iframe shrinks in height.
We never expect all issues can be resolved but it would be good to set our expectation. Renaming the function to FB.Canvas.setAutoGrow at least tell us what it can handle and reflects its functionality.
This is actually what Facebook has just announced.