Here is an article by Kip Adams that might help explain the earlier than usual antler shedding.
"In isolated incidents of early antler shedding, the bucks involved were probably injured during fall and cast their antlers early as a result. In situations where numerous bucks are involved or where bucks across several square miles cast their antlers early, nutritional stress, physical exhaustion from the rut, or a combination of the two are likely responsible. Nutritional stress can easily be confirmed or ruled out by assessing body weights, lactation status and/or kidney fat percentages from the does you harvested. This is one more reason to collect harvest data from every deer taken on the property you hunt and/or manage.
About the only bright side to early antler casting is it allows you to find sheds a little sooner!"