Forgotten?

“Yet did not the chief butler remember Joseph, but forgat him.” (Genesis 40:23 KJV)

At first reading of this verse, we often see this as a lesson to not forget those that have helped us out.  To not forget the goodness that God has done for us.  To remember what actually took place that caused us to make it to where we are.  I’m sure that is a great lesson, but is there a reason why God may have allowed the butler to “forget” Joseph?  We are told later in scripture, “Humble yourselves in the sight of the Lord, and he shall lift you up.” (James 4:10 KJV)  What is the best way for Joseph to know that it was the Lord lifting him up and not just someone returning a favor?