Tons of entries in sessions table

Basic authentication is essentially a stateless authentication mechanism, so the service provider would expect to receive the authorisation credentials for every request.

Combined with the way authentication takes place in Services module, this module needs to create a 'fresh' user login for every request.

So, although not ideal, it will end up with a new session entry per request, though these should be dealt with by Drupal's session garbage collection.

On second though, I've added a note on the project page which recommends using Session Expire module to limit this issue.