+matte and Layered PSDs

Hi folks,

It appears that using IM 6.6.3-0_0:

convert +matte source.psd test3.jpg

or

convert source.psd +matte test3.jpg

both result in

test3-10.jpg
test3-9.jpg
test3-8.jpg
test3-7.jpg
test3-6.jpg
test3-5.jpg
test3-4.jpg
test3-3.jpg
test3-2.jpg
test3-1.jpg
test3-0.jpg

with each JPG being a rendering of a layer in the PSD!!  -alpha off makes
no difference.  Flattened PSDs also result in a perfect JPEG, as expected.

With TIFF, the result is as expected: one JPEG, with the alpha channel(s)
ignored in rendering.

I believe this may be a recent change - layered PSDs in the past were
rendered just as TIFFs were.  Does this jibe with anyone else's experience?
I've tested it on three machines, including with a fresh install.  I could
also be misunderstanding the syntax of the matte switch?

Thanks for your attention to this!

- J