You are getting the house edge effect the longer you play so there is nothing special about having more continous reds because it is normal
What is the "house edge"-effect?
Whenever you're betting, you go against the odds of the house. If you win they lose, if you lose your money they win it. Statistically, the house-edge is a calculated percentage. If you roll your dice to infinity, the amount you will lose would be "Money_gambled x house-edge percentage". It's a guaranteed loss in the long run, you just can't outwin the house (theoretically speaking).