Cautious vs Careful

A: I lost my pen, can I borrow yours?
B: Okay, but next time you should be more cautious

Does this short dialogue sound okay? This was from an exam, the expected word for the blank where cautious is was careful, but one student wrote cautious. According to the dictionary it would seem these words have the same meaning, but none-the-less, it feels somewhat wrong to me.

I feel like cautious should be used in a specific situation, whereas something like losing a pen is just a matter of daily life, so careful seems better. Since I don't know my grammar well, I'm just going on my "gut-feeling" as a native speaker, but because I don't know of anything wrong I can't say that the student is wrong either.

Can anyone help? Thanks.