Hello, long time admirer, first time poster.

I am running a box with Plesk 9.5 and the following from art repos:

mysql-libs-5.5.27-11.el6.art.x86_64
mysql-5.5.27-11.el6.art.x86_64
php-mysql-5.3.15-7.el6.art.x86_64
mysql-server-5.5.27-11.el6.art.x86_64
mysql-connector-odbc-5.1.5r1144-7.el6.x86_64
mysqlclient16-5.1.59-2.el6.art.x86_64

Phpmyadmin is showing a warning that:

"Your PHP MySQL library version 5.1.59 differs from your MySQL server version 5.5.27. This may cause unpredictable behavior."

Is this normal? I do not seem to be seeing any issues on the server, but I'd rather avoid any if I can.

Thanks again for your help.

There's three options

1. Switch from php-mysql to php-mysqlnd, which doesn't use mysqlclientXX. That's why you're getting that notice, because mysqlclient was compiled against a previous version.
2. Ignore the error. It's harmless.
3. Compile your own