In The Dressing Room

So I have to admit that I love shopping, even if I'm not buying stuff.  Shopping has always been really therapeutic for me.  So one evening after a really tough day, I decided to go to the mall to relieve the worries of the day.  Part of the difficulties of the day was that I was really horny, had no significant other to do anything with, and just wasn't feeling up to masturbating, plus I was at work for much of the day anyway.   As I walked through the store, I gathered a few things to try on.  There was another woman shooping in the store, older 20's or so, absolutely beautiful.  She had beautiful, voluminous, wavy blonde hair, the kind that makes just about any woman jealous.  I noticed that she gathered a few items and headed into the dressing rooms.   A few minutes later, I headed in there myself. As I entered the dressing rooms, I noticed all of the doors were closed.  I usually like to be in a stall away from other people, but I couldn't really see any feet under the doors from where I was standing.  I decided to try one door, and knocked on it.  No answer, so I opened the door.  To my surprise, the blonde girl was in there, standing there in just her bra and panties (a pair of beautiful, lacy gray and white striped bikinis).   She was surprised and turned to me and said, "I didn't realize you were knocking on my door, i thought it was a different door!"   She was so embarrassed.  I too was moritified, but inside, I also thought it was slightly funny and even a turn-on.  I apologized, closed the door, and found another room.  I tried on a few items, and thought that the humor of the situation broke the tension of my otherwise crappy day.   Yet, even as I tried on clothes, I couldn't shake the image of her in her panties that was burned into my brain.  I could feel my horniness growing, and my panties getting damp.  In my mind, I kept replaying the opening of the door.  I saw her in her panties, and it was all over.  I knew I had to get some relief, and it couldn't wait until home.  I sat down on the bench in the dressing room stall, took off my panties, and started masturbating right there, mostly to the image of her in her panties.  It was hard for me to keep quiet, especially hard as my fingers made slight sounds I was slipping them in and out of me.  It didn't take long for me to cum, and I managed to stifle my moans as my orgasm washed over my body.  i wasn't quiet enough though, because someone was passing by and said "are you ok in there?"  I answered yes, hoping that they wouldn't open up the door.  It never moved. I used my panties to clean up my wetness, as they were already trashed anyway.  I stashed them in my purse, resigned to returning home commando.  I slipped my dress back on, and made sure I looked presentable. I gathered the clothes I brought to try on, deposited them on the return rack, and slipped back out into the store.  As I passed the sales rack right outside the dressing room, I saw her again.  As I passed her, I said "i'm sorry that happened, but you should know those panties are really cute and they look awesome on you."   She replied "they must, because it sounded like you enjoyed yourself in there."   I think I was more shocked than she was when I walked in on her.