This passage continues the saga of Samson’s time with Delilah, who seduced him to tell her the source or secret of his great physical strength. After he told her that it was his long hair, she then had him sleep and she called for some men to cut off his hair, 

Then she lulled him to sleep on her knees, and called for a man and had him shave off the seven locks of his head. Then she began to torment him, and his strength left him (Judges 16.19). 

The Bible reveals that Samson had been a Nazarite, which meant that he had not cut his hair since the day of his birth. However, the Bible never argues for the secret of his strength being in the fact that he had woven his long hair into seven locks.

Therefore, we see no significance to the fact that his hair had been woven into seven locks.