I ran across this problem too. The fix was to make sure each event returned in the JSON included an "allDay" name/value pair set to false.
[{'title': 'Successful','allDay': false,'start': 1266398223,'end': 1266398266,'url': '/shlk/cgi-bin/getshlkrunlog.pl?i=21'}]
Or set allDayDefault to false:
$('#calendar').fullCalendar({
...
allDayDefault: false,
...
});
grapenuts
2010-02-19 19:52:37