Bob,
Drill out the rivets and give a try at straightening the brackets. Long as there are no cracks and your rivet holes are still the original size, you should be OK. If in doubt, give a call to Van's support.
Some have suggested bending the tips of the two outside brackets (up by the bearing) inward slightly prior to assembly to keep them from bending outwards when riveted. Also make sure that the center bracket piece is perfectly straight. Mine were bent slightly and had to be straightened prior to assembly.
Other hints mentioned in the past have been to rivet in a random pattern, don't over squeeze the rivets, make sure the bearing relief on the brackets is perfectly clean (no primer) and that the reliefs are actually deep enough so that the bearing is not pressing outward.
Along with what I have mentioned above, there are some other causes/solutions mentioned in previous postings. Try a search on "flaperon hinge bracket assembly" or something similar.
Alex