Not much mention of Uncle Mo throwing a shoe at the start - "If's" and "But's" granted... but considering the margin of defeat it isn't beyond possibility that he wins by lengths...
http://www.nytimes.com/2011/08/28/sp...by-a-nose.html
>>>He got there and found little consolation when his trainer, Todd Pletcher, told him Uncle Mo had hopped at the start and lost the shoe on his right hind leg. <<<
If you believe TAP's assessment of the start, then I don't know what the cause for alarm would be.