[man]time/man returns you a unix timestamp which includes the number of seconds since the Epoch (Jan 1st 1970). This means that unless your time in the database matches this value down to the second you will never see red.
What you want to do is convert both of these timestamps into date values then back to timestamps, basically stripping the seconds (really setting them to be the midnight on the day):
$date = mktime(0,0,0 date("m", $row["date"]), date("d", $row["date"]), date("Y", $row["date"]));
$notes = $row["notes"];
$current_date = mktime(0,0,0 date("m"), date("d"), date("Y"));
/* Rest of code remains unchanged */