Visible filler thread after tear trough treatment! 3 days post op, is this permanent? (photos)

You are correct in saying it is early days but it does look as if the filler has been placed slightly too high. If it is a HA filler and is in the correct plane depth-wise it should be massageable into the right position. If it is too superficial, it will need dissolving. I suggest you go back to your injector sooner than the standard 2-week review and see what they can do. If it needs dissolving and re-doing, and reputable injector would not charge extra for that. Good luck! 

Thanks for sharing your pictures and your question.  The skin under the eye is extremely thin and unforgiving, especially if the filler quantity used is too large or not injected by an experienced physician.  Without knowing the exact product used in your case, or the amount, it is hard to give a definitive opinion.  However, in most cases, I would allow for a minimum of one week to pass from the time of injection for complete resolution of the swelling, and to allow the product to completely settle.  If it still bothers you when you look in the mirror, or has an aesthetically displeasing appearance that you feel is worse than pre-injection, I would consider dissolving it.  Hope this was helpful.