The symptoms of using the wrong fluid, be it +3 or some other ATF, is usually a fluttering or slipping during your upshift, not a thump during your downshift.
Either way though, some other ATF plus their special additive can be very bad for these 41te transmissions. If they didn't use ATF+4 demand that they flush it and use the proper stuff, as per the Dodge service manual. At best it can keep the transmission from learning properly (or slip/flutter), worst case, it will kill it. I would see to it that it was done right.