I recently had a septoplasty and blew my nose on day four of recovery, will there be damage?

I generally advise patients to wait until their one week follow up appointment to begin blowing their nose due to an increased risk of bleeding. Although your are unlikely to have caused any long term damage by blowing your nose, your concerns about a stent or splint inside your nose warrant a phone call to your surgeon to make sure you have not disrupted his or her handiwork.

Though it is not advisable to blow your nose this
early into recovery, you definitely took the right approach by being as gentle
as possible. From the description you have provided, it is highly unlikely that
you have permanently affected the results of your septoplasty. It is true that your nose is still healing and
will be for a while, but it would take more force for actual damage to have
been sustained. My best advice would be to schedule a follow-up visit with the
surgeon who performed your septoplasty to evaluate your condition in person and
to make sure that everything is going smoothly in your recovery.

It's unclear in your question whether you just saw the stent, or whether you actually removed it.  Regardless, it would be very difficult to cause permanent damage to your septum (even on post-op day 4) with gentle nose-blowing.  I tell patients not to blow their nose for one week after surgery because it can increase the chances of a nosebleed, not because it can affect the final results of the surgery.  I do recommend, however, that you consult with your surgeon promptly. If you are worried enough to post a question to this forum, your concerns warrant a trip to the doctor.