Living in a multi-citizenship situation, and having transited thru the US "a lot" in my travels, I can relate that they are very strict about "what" nationality you are going to use at that exact moment when you approach the counter.

I wouldn't bother with it personally. They are going to ask why, and I don't really think opening up an irregular route of questioning with any border official anywhere, especially an American one, is generally overall, a wise decision.

Welcome to the forum BTW.