Michibiki 2 and H2A second stage observed?

For several minutes around 01:18 UTC June 1, from a point about 70 km south
of Mendoza Argentina (33.546S, 69.008W), we observed what appeared to be a
venting (~30 arcminute dia. visible cloud) and slowly rotating (on the
order of 1 RPM from the double pinwheel plumes seen via 16" telescope)
rocket body.  Nearby (a few arcminutes away) was another comoving but
slowly separating satellite.  Both were moving very roughly west to east,
and overhead at about 01:18 UTC.

Can anyone confirm that this was likely a venting H2A second stage and its
recently (~26 minutes prior) separated Michibiki 2 payload?  Angular speed
was much slower than typical LEO sats, consistent in my mind with a GTO
launch (which I've never knowingly seen before though).  What I don't know
is launch azimuth/TLE of Michibiki 2, and whether it (and launch time) is
consistent with flying over Mendoza at that time.  Thanks for any input.

-Kai
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