vShield login/logout of vCentre

So I had an issue with my vCentre database size, which I've managed to resolve (issue discussed here)

The database had grown huge due to vSheild manager logging in and out many times each second.  Only way to stop this was to disable the service account it was using. 

I'm assuming this isnt "normal" behaviour.  Can't see a reason as to why vSheild manager would need to resync so often.

Thanks,