AM i overthinking? what is the normal reaction in this situation?

I'm not sure if i'm over thinking this issue, so please try to step in my shoes and see what you think about it.

Okay, so there is Friend A who is like a really good friend to you and you two text each other every single day. And then there is a friend B, who is also friends with Friend A, and they go to the same school. With Friend B, you two are good friends but not as close, and rarely talks to each other unless you guy met. Okay, so Friend A tells you that friend B is leaving the country( for holiday) tomorrow. And you ask Friend A why didn't she tell you earlier. And Friend A said that because Friend B is always joking about going or leaving places, so she thought this was a lie again, but it turned out to be true.

Would you believe what friend A said?Would you feel upset to the fact that friend B didn't tell you personally? Or that friend A didn't tell you earlier? Would it be better if friend A tell you a day earlier?