I had the same surgery a year ago and I am still having major post-nasal drip.
I am seeing my doctor tomorrow (or Thursday - he may have to cancel)- either way I will let you know-- I asked yesterday and the receptionist said it was -- but I never trust receptionists (or doctors, for that matter -- they never want to look like they may have caused something) - Good luck!!
I had sinus surgery/septoplasty in Aug. And for the past month or so have developed massive post nasal drip. I'm quite worried about it myself, but don't see my surgeon until the 18th. Since you are so close to your surgery, perhaps you can call your surgeon and ask if this is normal. And I do gag once in awhile. So will be bery interested in what answers you get. Hang in there. I doubled up on Zyrtec, which helps me quite a bit. Please post if you get an answer from your doc!