I just recently found out that my GG grandmother - Mary Ellen Cage (b. Nov 1, 1834 in prob. Greene Co., PA. She married William Black.) was the daughter of "Wm. Cage" & a "Hogan" who was born in Ireland. I think that's a Hagan. He's in the 1840 census in Greene Co. age 20-30, with a wife and 2 daughters. I think he is the same as your's, as he no longer appears in PA. He is apparently the William Cage in 1850 Lee Co, Iowa and 1860 Shelby Co., Indiana.
Have you been able to find anything more on William?