Is it normal for a tiny pin sized hole to form after a healing wound?

A cyst has a small pore that communicates with the outside.  Usually that pore is removed along with the cyst.  It sounds like that may not have been done in your case.

Thank you for sharing your question and I am sorry to hear of your recovery issues.  Unfortunately without photographs it is difficult to offer advice and I would recommend seeing your dermatologist for an in-person exam.  A separation that occurs months after the original surgery is concerning for either  a suture that has worked itself to the skin surface or a possible recurrence of your cyst.  Hope this helps.