Indefinite subscriptions being renewed

In the news section of the membership dashboard i'm getting a lot of entries that look like this:

[ 2014-02-07 : 10:51 ] John Doe has moved from level Educator - Standard on subscription Educator Network to level Educator - Standard on subscription Educator Network

This particular subscription is free and set to indefinite (see attached screenshot for settings)

This is a problem because it is retriggering a ping i have setup for when they initially subscribe. Is there a reason why this is happening and/or how can I stop it?

Thanks