David,
Might I suggest you release the source (as you did) with some sort of official license (plenty of different open source licenses to choose from, beer or BSD fan myself (see
http://opensource.org/licenses/ )). There seems to be community interest in your application and would hate for either somebody to rebrand it as their own or for you to take ownership of a future release somebody created based on your initial code release. As a developer myself 'You may consider the latest Version as open source' is extremely vague and doesn't spell out exactly what a developer can or cannot do with your code.
Not saying this will happen and we are a small community but there are always those off chances.