opencv train cascade in less than 2 hours

I'm new to opencv I want to detect a fire object and I'm training a fire classifier using opencv traincascade, as I read various tutorials everyone said that training will use up days or even weeks. I have 700 positives and 3k negatives, I read that I should not use all positive to train and ratio of 1:2 in positive negative so this is what I inputted opencv_traincascade -data classifier -positive.vec -bg negatives.txt -numPos 500 -numNeg 1000 -numStages 20 -minHitRate 0.999 -maxFalseAlarmRate 0.5 -precalcValBufSize 1024\ -precalcIdxBufSize 1024 -mode ALL PAUSE the training only took 2 hours, Do I need to worry about it? is there something wrong with my samples?