Beagle growling

Question
Hello, I have a 3 month old female beagle. She's really playful and close to the family. Although, there is only one situation that she growls a bit. This is when I train her to fetch. Sometimes she will be able to do the command but once or thrice when she retrieves the ball, he will pass me by and growl a bit and then play again with the ball. I'm thinking that she maybe tired or not in the mood. Although, she still goes after the ball and when I retrieve the ball from her she doesn't growl at all..The only time she growls is when she retrieves the ball and passes me by with a short growl. Even if she is eating we can pet him and move his food and she doesn't growl..or when she's playing with a toy we can even get the toy without her growling..So, I'm thinking she's not aggressive..It's just that maybe she's tired or not in the mood..Is this normal? What I do is when she growls...I immediately get the ball and stop the training/playing and I tell him "No" or "bad" then I put him in the garage. Is this an aggressive behavior or just a temperament of the dog? Am I doing the right thing? I've been training her to fetch for 3 days now..She's responding most of the times but sometimes with a short growl, although she'll still give the ball...What do you think is happening in this situation? Thanks! :)

Answer
She sounds like a great beagle and not aggressive! At 3 months she is still learning her place in the pack but, from what you have told me, she doesn't seem like an aggressive pup. Nor does it seem like she is attempting to challenge you for authority. I also do not think she is tired or not in the mood to play anymore.  
To me it sounds like she wants to play with the ball with out having to go get it every time =). Lab's are natural born fetchers; Beagles are not. I have not seen to many beagles that like to fetch. Most of them think "Why should I get that ball when all they are going to do it throw it again"? Most dogs love balls (especially tennis balls) because they are semi-soft and they can chew them. They make great chew toys especially for teething pups. If this seems like the case with your beagle maybe you can throw the ball twice then let her keep it for a few minutes the third time. On the third time just go over and pet her or rub her back. I have a beagle that would rather put the ball down and roll on top if it then go fetch it.
You are doing the right thing by not letting her growl at you for ANY reason. You are right to stop playing and telling her "No". I wouldn't recommend totally stopping playing or training all together and putting her in the garage. One minute of stopping play is a like a lifetime for a pup. If you stop playing for a minute and turn your back to her she will understand if she growls she will lose her playmate.
Another thing you may want to try is having her fetch another toy or stick and when she returns it to you give her the ball as a reward. If she readily gives you the other toy for the ball you know that she wants the ball more then she wants to go fetch it. This way she still gets the exercise of fetching, gets to play with the ball and the companionship of her owner.

Fellow beagle lover,

Ken