When reindexing a user's mailbox, the following appeared in mailbox.log but did not show as a failed reindex in the admin UI. Is this error benign or is it something we should investigate further?

Thanks!
Mark

Code:
2008-05-09 13:36:42,952 WARN  [Thread-3977] [] index - exception while parsing message; message will not be indexed
javax.mail.MessagingException: No inputstream from datasource;
  nested exception is:
        java.io.IOException: failed to get raw input stream for mime part
        at javax.mail.internet.MimeMultipart.parsebm(MimeMultipart.java:718)
        at javax.mail.internet.MimeMultipart.parse(MimeMultipart.java:452)
        at javax.mail.internet.MimeMultipart.getCount(MimeMultipart.java:229)
        at com.zimbra.cs.mime.Mime.handleMultipart(Mime.java:233)
        at com.zimbra.cs.mime.Mime.handlePart(Mime.java:221)
        at com.zimbra.cs.mime.Mime.handleMultipart(Mime.java:237)
        at com.zimbra.cs.mime.Mime.handlePart(Mime.java:221)
        at com.zimbra.cs.mime.Mime.handleMultipart(Mime.java:237)
        at com.zimbra.cs.mime.Mime.handlePart(Mime.java:221)
        at com.zimbra.cs.mime.Mime.getParts(Mime.java:162)
        at com.zimbra.cs.mime.ParsedMessage.parse(ParsedMessage.java:256)
        at com.zimbra.cs.mime.ParsedMessage.analyzeBodyParts(ParsedMessage.java:354)
        at com.zimbra.cs.mime.ParsedMessage.getFragment(ParsedMessage.java:668)
        at com.zimbra.cs.mailbox.Message.generateIndexData(Message.java:527)
        at com.zimbra.cs.mailbox.Mailbox.indexItemList(Mailbox.java:3510)
        at com.zimbra.cs.mailbox.Mailbox.reIndex(Mailbox.java:1786)
        at com.zimbra.cs.service.admin.ReIndex$ReIndexThread.run(ReIndex.java:157)
Caused by: java.io.IOException: failed to get raw input stream for mime part
        at com.zimbra.cs.mime.Mime$FixedMultipartDataSource.getInputStream(Mime.java:327)
        at javax.mail.internet.MimeMultipart.parsebm(MimeMultipart.java:712)
        ... 16 more
Caused by: javax.mail.MessagingException: No content
        at javax.mail.internet.MimeBodyPart.getContentStream(MimeBodyPart.java:578)
        at javax.mail.internet.MimeBodyPart.getRawInputStream(MimeBodyPart.java:597)
        at com.zimbra.cs.mime.Mime.getRawInputStream(Mime.java:304)
        at com.zimbra.cs.mime.Mime$FixedMultipartDataSource.getInputStream(Mime.java:325)
        ... 17 more