"runaway argument" exporting: * _is_?

[Greg Minshall <minshall@umich.edu>]

hi.  i'm running
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Org-mode version 8.0.1 (release_8.0.1-42-g267cbe @
/Users/minshall/usr/share/emacs/site-lisp/org/)
----

my test case is
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#+DATE: <2013-04-25 Thu>
#+OPTIONS: H:2 texht:t
#+BEAMER_COLOR_THEME:
#+BEAMER_FONT_THEME:
#+BEAMER_HEADER:
#+BEAMER_INNER_THEME:
#+BEAMER_OUTER_THEME:
#+BEAMER_THEME: default
#+LATEX_CLASS: beamer
#+LATEX_CLASS_OPTIONS:
#+LATEX_HEADER:
#+LATEX_HEADER_EXTRA:

* _is_?
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exporting via "C-c C-e lO" (or, "lo"), i get an error from latex.

if i change H:2 to H:1, all (seemingly) works.  here is a diff of the
.tex file generated by each H:
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bash greg-minshalls-mbp: {1039} diff sectbug.texH:1 sectbug.texH:2
38,39c38,39
< \begin{frame}[label=sec-1]{\underline{is}?}
< \end{frame}
---
> \section[\underline{is}?]{\underline{is}?}
> \label{sec-1}
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am i doing something wrong?  (this is fallout converting from 7.9.3f to
8.)

cheers, Greg Minshall