Strange spacing with gathered and aligned

for some reason, a one-line "aligned" is not properly centered. this appears to be a bug, and i am entering it as such in the amsmath bugs list.

this (unwanted) result can be easily demonstrated by two additions to your test file:

(1) replicate the (simple) example with the content of the first aligned duplicated, to give a two-line aligned;

(2) replicate the same example replacing the first aligned element by

  q = r \,, \quad
  x = y \,, \quad
  z = w \,,\\

the modified elements will be centered as expected. i haven't determined the reason that the one-line aligned element is shifted to the left. however, for the purpose of posting the problem to the bugs list, the reason isn't necessary; a demonstration is sufficient.

please consider sending reports of problems with amsmath directly to [email protected] .