When/why did the [N]RSV become a "Catholic" Bible instead of a "Protestant" Bible? The Methodist church my aunt grew up in back in the 50s and 60s relied almost exlcusively on the RSV, and she continued to use it until her death a few years ago as her preferred translation.

However, when going through Christian bookstores (or just Christian sections of bookstores) today, I see the RSV (and NRSV) group with the NAB and other "Catholic" Bibles.

When/why did this occur (at least in the US)? 

Are there aspects of the RSV/NRSV considered less ideal to Protestants now that were not as widely known/cared about half a century ago?
The reason that many of them are considered "Catholic" is probably because there is now a "Catholic Edition" of the RSV and the NRSV. Both of these are gaining traction over the NAB if only because of the superiority of the translation. 

The major difference between Catholic and Standard RSV is that the Deuterocanon is placed in the standard Catholic order and there are a number of small word changes (most notably "brethren" for "brother").