Spacing problem with microtype and Hoefler Text under xelatex

I'm seeing an odd spacing problem with microtype and Hoefler Text under XeLaTeX. A minimal example is provided below. When typeset with xelatex, the word "he" and the emphasized word "ought" overlap as shown here:

The problem disappears if I use a different font (e.g., Palatino), or drop the microtype package, or even drop the first sentence. Any insights as to what's causing this problem greatly appreciated.

\documentclass{article}

\usepackage{microtype}
\usepackage{fontspec}
\setmainfont{Hoefler Text}

\begin{document}

For some cause, which I could not at the moment divine,
Arthur was unusually grave and silent during our walk home.
It could not be connected with Eric Lindon, I thought, as he
had for some days been away in London: so that, having Lady
Muriel almost ‘all to himself’—for \emph{I} was only too
glad to hear those two conversing, to have any wish to
intrude any remarks of my own—he \emph{ought},
theoretically, to have been specially radiant and contented
with life.

\end{document}


Update for reference: I'm using current versions of TeX Live 2013, microtype (2.5a) and XeLaTeX (0.9999.3) as described in the questions below.

• Does it occur if you use he~\emph{ought}, ? – bombcar Mar 25 '14 at 2:55
• I had to use \setmainfont[ItalicFont=HoeflerTextItalic.ttf]{HoeflerText.ttf} because the font is only installed on my system for use with pdfLaTeX (not system-wide). However, the example then compiles fine without the issue shown in the image you posted. Perhaps it is a bug in the version of the font you have? Or perhaps your TeX installation is not current? – cfr Mar 25 '14 at 3:04
• It doesn't happen with my Hoefler Text.ttc in the system fonts (version 8.0d2e1). – egreg Mar 25 '14 at 7:42
• Your MWE works fine for me too. Since the problem goes away if you take out microtype, then perhaps you have some broken local microtype settings for Hoefler. – Thruston Mar 25 '14 at 9:39
• @bombcar: Unfortunately, the problem still occurs with he~\emph{ought}. – Stuart Mar 25 '14 at 18:08