Did Samson let his hair go wild, or did he do something with it? As Delilah prodded him to tell her the secret to his superhuman strength, we read this,

Delilah said to Samson, “Until now you have mocked me and told me lies. Tell me what you may be bound with.” And he said to her, “If you weave the seven locks of my head into the web of the loom”— (Judges 16.13). 

He did something with his hair, putting it into seven locks, but does that mean “seven” has significance in reference to his hair? I do not believe so, unless the Bible had made an issue of it. The Bible only signifies the length of his hair, or more precisely, that it had not been cut, not that he had it in seven locks.

Therefore, this appears to be an incidental reference to seven.