meaning of "べつにいいけど"


I recently skyped a friend just to ask how her English studies were going.
During the conversation, I think I said something like:

> "なんか、英文の質問があれば、どうぞ。ま、べつにいいけど。"

She seemed to think my usage of "べつにいいけど" was hilarious. But, I could not
understand her explanation as to why.

I intended to say:  
(-) " _If you have any English grammar questions, please ask._ "

Without much thought, I tacted on a "べつにいいけど" just to mean something like:  
(-) " _Hey, if you don't have questions, that is cool. I am just here if you
the help._ "

> What is so funny about saying 「べつにいいけど」 in that context?  
>  In what context could 「べつにいいけど」 be used and not sound funny?  
>  What are more examples where 「べつにいいけど」 sounds funny?

Or, am I just not understanding something more?




This set phrase "別にいいけど" is typically used with complaint or criticism, like
so:

> 今晩はカレーじゃないのか。まあ、別にいいけど。
>
> 昨日のテストは満点じゃなかったのか。別にいいけど。

This basically means "although it's not really a big problem."

But I think this expression often sounds more curt/rude than it looks. It's
almost "after all, I'm not very interested," "who cares?"

> なんか、英文の質問があれば、どうぞ。べつにいいけど。

At least you need to say "if you don't have questions" in this sentence.
Without it, べつにいいけど doesn't make quite sense. Or maybe it's like you are
suddenly saying "after all, your question doesn't matter to me" or "I'm not
really expecting your question."

If you want to kindly say "never mind if you don't have any question for now,"
something like this is OK:

>   * 特に質問がないなら、構いません。(polite)
>   * （質問が）ないなら、気にしないで。(casual)
>   * ないならないでいいよ。(casual)
>




This set phrase "別にいいけど" is typically used with complaint or criticism, like
so:

> 今晩はカレーじゃないのか。まあ、別にいいけど。
>
> 昨日のテストは満点じゃなかったのか。別にいいけど。

This basically means "although it's not really a big problem."

But I think this expression often sounds more curt/rude than it looks. It's
almost "after all, I'm not very interested," "who cares?"

> なんか、英文の質問があれば、どうぞ。べつにいいけど。

At least you need to say "if you don't have questions" in this sentence.
Without it, べつにいいけど doesn't make quite sense. Or maybe it's like you are
suddenly saying "after all, your question doesn't matter to me" or "I'm not
really expecting your question."

If you want to kindly say "never mind if you don't have any question for now,"
something like this is OK:

>   * 特に質問がないなら、構いません。(polite)
>   * （質問が）ないなら、気にしないで。(casual)
>   * ないならないでいいよ。(casual)
>

