Hi Terrie, Casper is a handsome boy- thanks for sharing that photo with us. The others have given you good advice- I don't think I'd take the bell away either- why not let him have a little fun with it? He may be a little crabbier if he is being hormonal, but if you watch his body language you should be able to avoid a bite.
I imagine the vet was talking about the fact that a female may lay eggs and the associated risks that come with that- that is my guess....however, if an egg was laid, then you would know for sure without a DNA test!