I can see this as being a very phycological level for various reasons.
1. It has retested and not broken resistance back to back on the monthly 6 times in 2 years.
2. Price created a sell trap last month by giving a bearish engulfing and then a retest like a head and shoulder pattern. However the pattern never completed and the retest was completely bullyish engulfed as of yet.
3. Based on all these factors I can see most traders selling. Because that's just what they do. They take the first pattern they see, and just be eager and desperate and inpatient.