I have a small white pine in my back yard that browned, but then recovered. I am sure that it is nowhere near the application of Imprelis. Of course, it could be coincidence, or not.
However, I think this is an interesting phenomenon. Either DuPont has created a disaster, or they have very unlucky timing.
But personally, I am not sure that it is sensible to expect a weed-free lawn, or that chemicals that kill weeds don't disrupt the biochemistry of other flora, or people for that matter. It seems odd to me that people spray their lawns with chemicals that are designed to be absorbed into cells with the specific purpose to interact with and often disrupt cellular machinery. On an inter-cellular level I am not that different from a weed. I'd rather keep away from those types of monkey wrenches.
People seem to believe that DuPont and other companies are able to create magical non-toxic herbicides. In actuality, they create toxins, and then test for specificity. If in their testing (on limited on time scales) they do not detect the adverse effects that they can detect, then to the market it goes. They really don't know the extent of the action of their product. Consumers complete the testing.