Fighting Words

Sometimes I don't realize how angry I am until something happens and a wave of rage rushes out. Today I tried to return something from one of the overpriced little shops in the neighborhood, something I bought yesterday on a whim, and I was told I could only have store credit. I refused to accept that, but my bargaining position was compromised by the tremor in my voice. I told the sales clerk that I would take it up with American Express, and she said, "hmmmm" in a condescending way, which I told her was inappropriate for dealing with a customer, and she said she was only speaking in the manner in which I was addressing her. Something made me stop before I completely lost it. I took the store credit, called Amex on my cell as I walked out of the store, and found out I can't dispute the charge until 48 hours after it occurs, but I can call tomorrow. I don't know why it's suddenly so important to me that I win this battle. Where is this anger coming from? It's not just because I paid $60 for a wallet that won't close in a store where size 6 is in the large section. Or is it?