Please find my logwatch results for vsftpd service. i am running updated vsftpd on centos-4.1 and still i am getting some probes.

Could someone put some light on this issue. I am little worried about these probes.

Sure. Some bot is checking you for exploits, or other vulnerabilities available via FTP. If this has to be public ftp, make sure to keep your system updated, use selinux, and you may consider limiting NEW connection types via iptables, which should slow down junk like this.

If it's ftp just for you and some friends, restrict it to known ip addresses or use sftp/scp instead.