repacked bearings and now brakes seem weak

I actually blew the drums and the brake areas with my electric leaf blower to get the dust off. I stood back and did not breath in the dust. I then cleaned the brake shoes, magnet, and inside the drum with brake cleaner. I figured this was okay since it is brake cleaner. Once the bearings were cleaned and repacked with fresh grease, I put it all back togeter. For each wheel, before I lowered the wheel down, I spun it by hand and had my son hit the brake to make sure the brake was working. However I did not adjust the brakes since they were working fine before the repacking. I guess I'll try adjusting them as mentioned. It just puzzles me that they got weaker.