Sometimes I get home from work late and its already dark. I still like to throw bumpers to my 14 wk old pup. She seems to have a great nose because she hunts until she finds all of the bumpers even the ones she obviously doesn't see (they have a wing taped to the bumper for scent). I've been pretty excited about it. Is there any reason I shouldn't be working with her in the dark? As long as she's being successful I thought it was alright.