NFS mounted stale redo log

We have come across a strange situation concerning redo logs that are NFS mounted. We have an Oracle database with 4 redo log groups with 3 members in each group. Of the 3 members, one of those member is NFS mounted remotely. From time to time, Oracle will mark the NFS mounted redo log member stale for a split second and then it's status will go back to normal. I had always thought once Oracle marks a redo log stale it remains stale until Oracle cycles back around through log switches. Why is Oracle doing this? Is there a parameter that will assure us the member remains stale? My theory is that the NFS mounted redo log is marked stale for such a short period of time that Oracle is re-synching it with the remaining 2 local members and moving on. Please help if you have any ideas. Thanks.

BTW. This is on Oracle 9.2 Received on Tue Feb 12 2008 - 12:13:59 CST