I just came back vs I've just come back.

Post by jupiterean
I went out for lunch then came back to work at noon. At 12:05PM I
could tell my boss "I just came back from lunch" or "I've just come
back from lunch".
Which sentence is correct in this case? When I started to study
English many years ago, the textbooks taught me to use the second one,
but I've heard Americans use the first one quite often. Naturally I'm
confused.
Thank you.

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Normally I wouldn't notice any problem with "I've just come back for
lunch," but the more I think about it, the worse it seems to me (an
American). Normally in American English, the present perfect is used
for things that happened at an unspecified time or times in the past
and could happen still or again in the present. But in your example,
"just" specifies a time in the past, which calls for the past tense.
In American English.

Is "I've come back from lunch a moment ago" correct in British
English?

By the way, this American would be far more likely to say, "I just got
back from lunch."

--
Jerry Friedman