manual final custo not correctly spaced

[eroux]

See

\documentclass[12pt]{book}
\usepackage{geometry}
\geometry{a5paper}
\usepackage{fontspec}
\usepackage{gregoriotex}
\gresetlastline{justified}
\begin{document}

\gabcsnippet[0]{(c4) (f) (gh) (h) (h) (h) (hr) (hr) (hr[ev:\hfill]) (hg) (ixgi) (h) (hr[ocba:1;7.5mm]) (hg) (gh) (;z) (f) (gh) (h) (h) (h) (hr) (hr) (hr[ev:\hfill]) (hg) (ixgi) (h) (hr[ocba:1;7.5mm]) (hg) (gh) (;//h+)}

\end{document}

in which the spacings at the end of the two lines are different.