RSI failing to make new highs, for such a long time, while price is pushing marginally higher each time. In the last push price failed to reach to the resistance line, with the gap shown with green box. On the other hand, RSI keeps penetrating below 40, which is rare to see in a strong up trend.
These are all signs that a short position is justified. Please wait to make sure RSI wouldn't go above 65 this time, to add more reason for a weakened trend, hence more confirmation for a short.