syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or FTS_NUMB or '('

syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or FTS_NUMB
or '('

I have many messages like the following in /var/log/mysqld.log What does
it mean?
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$
syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or
FTS_NUMB or '('
syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or
FTS_NUMB or '('
syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or
FTS_NUMB or '('
syntax error, unexpected $end, expecting FTS_TEXT or FTS_TERM or
FTS_NUMB or '('
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$
centos 6.4 Server version: 5.6.12-56 Percona Server (GPL), Release rc60.4,
Revision 393