This is an easy fix and it should work on most chargers that have this problem.
I had this problem with the Griffin PowerJolt Dual Universal Micro that I bought for my TouchPro2. To fix it all you have to do is open up the housing (make sure you don't lose any parts, some are under tension and have the tendency to fly away) and solder together the two middle solder points on the usb connector. I have attached an image of what you should look for.Just make sure you do not accidentally solder to either pin 1 or 4 as they are the +V and -V. Once you solder the middle pins together you should be able to reassemble the charger and you phone should see it as an ac charger and will be able to charge faster. Let me know if this works for you.