irregular flares in Iridium-like path

On the evening of August 21 (2047 CDT, which would be 0147 UT on
the 22nd), I noted three bright, slow, and irregular flares from
an object moving northward across Ursa Major (the path went
about halfway between Eta UMa and Alpha CVn, and would have gone
almost in front of Epsilon UMa after it disappeared). The flares
were magnitude -2 to -3, and lasted many seconds at roughly the
same brightness. The location and path would be appropriate for
anorbit like Iridium 90 (and itc coplanar ilk), but this one
was moving northward rather than the southward motion that
those Iridia would have. This doesn't fit any of the non-operational
Iridium listings on heavens-above either. I was observing from close to
87.54W 33.21N.

Any ID hints will be appreciated!

Bill Keel