Plugin generating an error in error_log

I’m getting the following error from the plugin several times a day:

WHERE option_name LIKE ‘\_transient\_timeout\_dfad\__%’
AND option_value < ‘1381764057’
made by shutdown_action_hook, do_action(‘shutdown’), call_user_func_array, dfads_purge_transients

Any ideas what the cause is or how to remedy it?

Thanks

http://wordpress.org/plugins/ads-by-datafeedrcom/