Who is that masked man?

In Genesis 37 we find that Joseph has been sent to check up on this brothers.  He's wandering around a field and low and behold a man finds him wandering there and tells him exactly where his brothers have gone--so just what are the chances of that happening?  Here's the text 15 And a man found him wandering in the fields. And the man asked him, “What are you seeking?” 16 “I am seeking my brothers,” he said. “Tell me, please, where they are pasturing the flock.” 17 And the man said, “They have gone away, for I heard them say, ‘Let us go to Dothan.’” So who is this masked man? How is it that he just "happens" to be wandering in this field. The Hebrew word for man here is just the typical word "ish", but you can't help wondering: Does Joseph look back on this moment as one of those moves of God that he speaks of in Genesis 50.19 But Joseph said to them, “Do not fear, for am I in the place of God? 20 As for you, you meant evil against me, but God meant it for good, to bring it about that many people should be kept alive, as they are today."  

So just who is this masked man?  A person who God providentially puts there?  An angel?  Whoever it is, God is at work.