Man from U.N.C.L.E. Section VII

I wrote a story that was something I personally liked a lot, and I thought it was clever. Sometime later I read a story by another writer that had been posted years before mine, had a very similar plot with very similar elements. Had I read it and not remembered? I shot off an email to her and apologized profusely for my unintentional misdeed, to which she replied it's just what happens in the genre.
Whew! And she's right, of course. Nothing new under the sun.