Personaly I would have folded her raise. However, the call was not soo bad, and I imagine it did your table image wonders there.
You had to show down your cards, and when they see you are willing to gamble with 84s, several things can occur. They can figure you are way too loose, or they can figure your not going to put up with any shinanigans, or they will start calling you more, or they will figure you are the luckiest sob they seen today.
All of those things can really shake things up, and if that call was outside your normal range, then the meta game benefits might have even compensated for a loss, which didn't happen.
Your read seems good, and you did get lucky you sob!!! you!