ProSites - Premium Themes can be selected/used by lower level users

Hi There,
I installed Pro Sites and I have to say it's great plugin and works well except one thing:
I have two levels defined in my network: 1. Agent 2. Broker. And then I enabled Premium Themes and assign one theme as the Premium Theme, with its minimal Level set to 2. Broker.
However, I found that for those users that are in the 1. Agent Level,from their admin panel, they can still select/activate/use it.

Is this a bug of the Pro Sites plugin?

Thanks
Leo