Absolutely.
You can do a couple of things.
1. Apply a custom signature set to the sensor in question; then 'uncheck' the signature that is causing so many alerts.
2. Or you can apply a filter so that it completely ignores the signature for the host or hosts that the DNS transfers are being directed against.
3. Finally, and probably the most recommended, is that under Tools->Notifications, you can specify how many alerts must occur before the first email/script is sent. THen specify how many alerts must 'pass' by before a second email/alert is sent out again.
If you're not talking about emails/scripts, then #1 or #2 are your choices.