I can see both sides of the argument...
Bottom line (to avoid confusion/argument/line-call-lawyers)...
* if my opponent disagrees with my partner's call, and ask's me, I only say, "My partner already made the call" (presuming I agree with/defer to my partner's call)
* if my *partner* asks me what I saw, then I'll answer honestly (ie. I didn't see it == good).
* If I *disagree* with my partner, and I'm certain (ie. i was in a better angle to make a call), I will confer with him/her (privately), and let them know I disagree, and let my partner correct themselves (I will NOT correct his/her call to my opponents).... (i don't recall the last time a partner has stayed with their call in this situation).