A spouse buying a firearm for the other spouse who is not a "prohibited person" is certainly not a straw purchase according to the intent of the law. I have bought all of my wife's growing assortment to avoid the typical gun store condescension and barnyard waste.
However, what you described falls into a gray area in terms of the wording.
BATFE used to have an online FAQ that stated that buying a firearm as a gift for a relative was not a violation of federal law. I can't find that particular item now.
(The FAQ is here:
http://www.atf.gov/firearms/faq/" onclick="window.open(this.href);return false;)
This document discusses straw purchases on page 165:
http://www.atf.gov/publications/downloa ... 5300-4.pdf" onclick="window.open(this.href);return false;
If the seller is not comfortable completing the sale on his terms, you're probably not going to persuade him to do otherwise.
- Jim