A bug in grep-command or I'm a bug.

[Henning Kvello-Aune]

I am attending Linux-consulent scool, and shoud do some training when I
hit this one: 
address@hidden ~]$ rpm -qa | grep ftp
ftp-0.17-33.fc6
lftp-3.5.9-0.fc6
ncftp-3.2.0-2.fc6
tftp-server-0.42-3.1
address@hidden ~]$ rpm -qa | grep ftp*
ftp-0.17-33.fc6
lftp-3.5.9-0.fc6
ncftp-3.2.0-2.fc6
libXft-2.1.10-1.1
libXft-2.1.10-1.1
fftw-3.1.2-3.fc6
tftp-server-0.42-3.1

I mean eg. the line libXft does not contain ftp(and something more). 
Is this a bug? If not but the error is me, please tell me why. 

Henning
Norway