luatex - misalignment of certain diacritics

%%% Local Variables:
%%% TeX-engine: luatex
%%% End:

\documentclass{article}[12pt]

\usepackage{fontspec}

\setmainfont{Linux Libertine}
\setsansfont[Scale=MatchLowercase]{Linux Biolinum}
\setmonofont{linlibertinem}

\usepackage{expex}
\usepackage{linguex}

\begin{document}

\noindent \underline{Not misaligned in normal environment}\footnote{Except something funny is happening w/ the mono/typewriter text, but perhaps that's a font-specific issue}\\

āsyàṁ mádhunā mr̥taṁ

\textit{āsyàṁ mádhunā mr̥taṁ}

\textbf{āsyàṁ mádhunā mr̥taṁ}

\textsc{āsyàṁ mádhunā mr̥taṁ}

\textsf{āsyàṁ mádhunā mr̥taṁ}

\texttt{āsyàṁ̇ mádhunā mr̥taṁ}\\


\underline{linguex:}\\
\exg. āsyàṁ̇ mádhunā mr̥taṁ\\
 mouth.\textsc{neu.nom.sg} honey.\textsc{instr} dead.\textsc{neu.nom.sg}\\
\trans ``the mouth, killed with honey''

\noindent \underline{Misaligned in Tabular:}\\
\begin{tabular}{lll}
  misaligned & mr̥taṁ & āsyàṁ̇ \\
\end{tabular}
\vspace{12pt}

\noindent \underline{Misaligned in hbox:}\\
\hbox{mr̥taṁ āsyàṁ̇}


% \underline{expex:}\\
% \ex
% \begingl
% \gla āsyàṁ mádhunā mr̥taṁ//
% \glb mouth.\textsc{neu.nom.sg} honey.\textsc{instr} dead.\textsc{neu.nom.sg}//
% \glft ``the mouth, killed with honey''//
% \endgl
% \xe