This looks very similar to https://issues.apache.org/bugzilla/show_bug.cgi?id=49837, a bug that now seems to have been fixed in the latest Apache FOP library (which is the library we're using for this export).
We'd have to test if this is really the same issue and if it is indeed solved if we start using the latest library, so it would be great if you could file a test project for this. However, the bug mentions that the problem is a soft hyphen character in the text (http://en.wikipedia.org/wiki/Soft_hyphen), can you verify this and see if the problem still occurs if you remove it?