out of sync - MYSQL

I have problem with mysql replication. Alarm trap turned me different position between Read_Master_Log_Pos and Position (difference of 1). This condition lasted about half an hour. I have this log :

Test: test_011... Waiting for master to send event $VAR1 = {
      'Master_SSL_Allowed' => 'No',
      'Relay_Log_Space' => '426719985',
      'Master_SSL_Key' => '',
      'Master_SSL_Cipher' => '',
      'Exec_Master_Log_Pos' => '877107263',
      'Relay_Master_Log_File' => 'log-bin.000020',
      'Master_SSL_CA_File' => '',
      'Replicate_Ignore_DB' => '',
      'Slave_SQL_Running' => 'Yes',
      'Master_Port' => '1111',
      'Master_Server_Id' => '20',
      'Seconds_Behind_Master' => '0',
      'Replicate_Wild_Do_Table' => '',
      'Connect_Retry' => '60',
      'Relay_Log_Pos' => '426719787',
      'Replicate_Ignore_Server_Ids' => '',
      'Last_Errno' => '0',
      'Skip_Counter' => '0',
      'Until_Log_Pos' => '0',
      'Last_Error' => '',
      'Last_IO_Errno' => '0',
      'Master_User' => '#######',
      'Master_Host' => '###.##.##.##',
      'Master_Log_File' => 'log-bin.000020',
      'Replicate_Do_Table' => '',
      'Relay_Log_File' => 'mysqld-relay-bin.000044',
      'Replicate_Do_DB' => '',
      'Slave_IO_Running' => 'Yes',
      'Replicate_Ignore_Table' => '',
      'Slave_IO_State' => 'Waiting for master to send event',
      'Until_Condition' => 'None',
      'Until_Log_File' => '',
      'Last_SQL_Error' => '',
      'Last_SQL_Errno' => '0',
      'Replicate_Wild_Ignore_Table' => '',
      'Master_SSL_Verify_Server_Cert' => 'No',
      'Master_SSL_CA_Path' => '',
      'Read_Master_Log_Pos' => '877107263',
      'Master_SSL_Cert' => '',
      'Last_IO_Error' => ''
    };

'$VAR1 = { 'Position' => '877280056', 'Binlog_Do_DB' => '', 'Binlog_Ignore_DB' => 'information_schema,mysql,performance_schema,test', 'File' => 'log-bin.000020' };

Anyone knows how to solve and analyse this problem?

This bug is related to out of sync - MYSQL.