NPE in describe_ring

Not sure how much of the following is relevant besides the stack trace, but here I go:

I have a 2 DC, 2 node per DC cluster. DC1 had it's seed replaced but I hadn't restarted. I upgraded to 0.8.4 in the following fashion:

-edited seeds
-stopped both DC1 nodes
-upgraded jars
-started both nodes at the same time

The non-seed node came up first and showed the following error. Then when the seed node came up, the error went away on the non-seed node but started occurring on the seed node:

ERROR [pool-2-thread-15] 2011-08-12 22:32:27,438 Cassandra.java (line 3668) Internal error processing describe_ring
java.lang.NullPointerException
at org.apache.cassandra.service.StorageService.getRangeToRpcaddressMap(StorageService.java:623)
at org.apache.cassandra.thrift.CassandraServer.describe_ring(CassandraServer.java:731)
at org.apache.cassandra.thrift.Cassandra$Processor$describe_ring.process(Cassandra.java:3664)
at org.apache.cassandra.thrift.Brisk$Processor.process(Brisk.java:464)
at org.apache.cassandra.thrift.CustomTThreadPoolServer$WorkerProcess.run(CustomTThreadPoolServer.java:187)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)