According to TomVH($)—and confirmed by Sam Webb and Josh Helmholdt($)—Michigan and 2013 Cass Tech OL David Dawson have parted ways. Dawson had wavered in his commitment back in July, when he mentioned at The Opening that he wanted to camp at Florida, and it appears that there's still serious interest in visiting Gainesville and potentially a couple other SEC schools. Given the visit policy of Brady Hoke's staff, if Dawson wanted to follow through on a visit he would no longer be considered a commit; my guess is that's what caused the mutual break.
While the Wolverines still have four blue-chip offensive line commits in Kyle Bosch, Chris Fox, Patrick Kugler, and Logan Tuley-Tillman, it's likely that they'll look to add one more to replace Dawson. While all of the current offerees on offensive line are committed to other schools, it's possible the staff looks to reconnect with IL OL Ethan Pocic, a current LSU commit who had very high interest before the available spots filled up, and IL OL Colin McGovern, a Notre Dame commit. If the staff decides to go after an unoffered prospect, the likely top target is Dawson's high school teammate, MSU commit Dennis Finley, who impressed at the Sound Mind Sound Body camp this summer.
UPDATE: 247's Steve Wiltfong reports that Dawson will take an official visit to Florida this weekend ($).
Also, Dawson sent out this tweet just a few minutes ago. I expect Michigan fans to show the same level of class: