The user agent you are seeing in logs is consistent with defaults of WordPress HTTP API:
'WordPress/' . $wp_version . '; ' . get_bloginfo( 'url' )
You can verify that requests are coming from your WordPress installation by using Core Control plugin’s HTTP logging module.
But from this information it is impossible to say why these requests are happening. It might be intended or not, as well as coming from core or extension (plugin/theme).