Quick question

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Feb 8, 2013 16:19
Why does ~たら show surprise when the part after it is used in the past tense?... for example:

家に帰ったら、誰もいなかった
アメリカに行ったら、たくさん太りました。

I feel so far like I understand the nuance of たら:

In "A たら B" I feel that you are saying "If A happens then B will chronologically occur afterwards".

That is, B is activated if/when A occurs.