Underscores inserted into compiled txt file

When I compile a short story in .txt format, “_” characters are inserted into the document that are not present in the sections of text that are being compiled. I may remember incorrectly, but I don’t think the last beta did that. I got four of them thrown in, all more or less at the end of a sentence:

  1. engelsk_.
  2. out."
    _
  3. pain._
  4. again_."

Steps to repeat:
Type 11k words in 8 sections in Scrivener
Use the “compile” button at the top of the screen. Choose “custom” and “Plain text”
Compile.

OS: Windows Vista
Beta version: 1.6