Although most issues of Esquire had their copyright renewed, a search of the U.S. Copyright Office's database shows that they seem to have forgotten to renew the February 1961 issue. Searching the database for "esquire feb 1961" does show that one story in the magazine, "Deep Scout," did have its copyright renewed by the writer, but the rest of the issue would appear to be unencumbered.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.