UDP responses on Mac OS 10.7/java 1.6

Hi,

I'm using dnsjava-2.1.3 on Mac OS 10.7 Lion and java 1.6:

$ java -version
java version "1.6.0_33"
Java(TM) SE Runtime Environment (build 1.6.0_33-b03-424-11M3720)
Java HotSpot(TM) 64-Bit Server VM (build 20.8-b03-424, mixed mode)

I'm unable to receive UDP responses.  For example, using the provided dig
class:

$ java dig @192.0.2.1 example.com
Exception in thread "main" java.net.SocketTimeoutException
    at org.xbill.DNS.Client.blockUntil(Client.java:43)
    at org.xbill.DNS.UDPClient.recv(UDPClient.java:124)
    at org.xbill.DNS.UDPClient.sendrecv(UDPClient.java:150)
    at org.xbill.DNS.SimpleResolver.send(SimpleResolver.java:257)
    at dig.main(dig.java:196)

I get the same result if I use the library within my own class as well.  I
can see the packets arriving on the wire using tcpdump, but the client
isn't picking them up.  However, if I use resolver.setTCP(true), then it
works fine.  It also works fine with ISC's DiG:

$ dig @192.0.2.1 example.com

; <<>> DiG 9.7.3-P3 <<>> @192.0.2.1 example.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37887
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0

;; QUESTION SECTION:
;example.com.            IN    A

;; ANSWER SECTION:
example.com.        2170    IN    A    192.0.43.10

;; AUTHORITY SECTION:
example.com.        171370    IN    NS    a.iana-servers.net.
example.com.        171370    IN    NS    b.iana-servers.net.

;; Query time: 2 msec
;; SERVER: 192.0.2.1#53(192.0.2.1)
;; WHEN: Mon Aug  6 12:26:58 2012
;; MSG SIZE  rcvd: 93

Any ideas?

Casey