这个是不算的，加拿大移民局官网上有明确的说明，如果你持有单次往返签证，并该签证还在有效期内，你从加拿大直接入境美国及其领土，并且只入境美国及其领土，那么返回的时候就不需要一个新的visa。但是返回的日期不能超过签证有效期。
A
single
entry
visa
allows
you
to
come
to
Canada
only
one
time.
Once
you
have
left
Canada,
excluding
travel
to
the
United
States
and
St.
Pierre
and
Miquelon,
you
will
need
a
new
visa
to
travel
back
to
and
enter
Canada.
If
your
visa
is
still
valid
and
you
are
travelling
only
and
directly
to
the
United
States
(including
its
Territories
and
Possessions)
or
St.
Pierre
and
Miquelon,
you
do
not
need
a
new
visitor
visa
to
return
to
Canada.
If
your
visa
expires
before
returning
to
Canada
from
one
of
these
areas,
and
you
are
not
in
possession
of
a
valid
visitor
record,
work
permit,
study
permit,
or
temporary
resident
permit
(authorizing
re-entry),
you
will
need
to
get
a
new
visitor
visa.