Warnings about what, though? We don't have anything that would warrant a rating above "PG," and we don't feel any need to create content that would raise it.
There was a thread about the "bugger" word, that was something above a "PG" rating.
The RPing aspect of the game is above a "PG" rating.
The content today doesn't have anything offensive, but are you willing to restrict the development so it will never have anything above it?
The fact that beer is served in a tavern.
The fact that there are guild that rp robbers and certain cases even drug dealers.
The fact that the kids might get solicited.
The fact that parents will one day come to you (as they always do) and say that since this is a PG rated game, you should always provide an environment were their 10 year old can safely play.
The fact that this is not a commercial game (maybe it will be one day?) and so, it doesn't absolutely have to grab the largest amount of players available expecting to get some cash or other type of support in return.
The fact you wouldn't have to spend as much time babysitting as a moderator.
Those are just some I could think of, no doubt people could come up with more...