First of, I am very sorry to hear this. Yes it is possible. I once saw a paper where 20% of aortic valve replacement patients needed work on their mitral valve later. But that was a paper on Ross patients and we dont know if they are the same or different from regular AVR patients. But I think (someone please correct me if wrong) such data is very hard to come by, so I think we know it can happen, but we dont know how often and when.
Second, I think the best approach is to deal with it and understand that you will need to get this fixed. You already know the drill and if you do need another OHS, your youth is on your side in terms of recovery.
Third, I would say that you should see a surgeon who specialises in reoperations. My surgeon's 'business' at Cleveland Clinic London was 60% reoperations. He also said that he replaced someone's aortic valve six times without issues before. So multiple reoperations can be done safely.
Finally and most importantly, you want to get a second opinion and try to speak to the best doctors out there on your issue. Clearly if it is OHS and since you are on warfarin anyways, a replacement would be sensible, as we never know how long a repair can last. Have you explored the mitraclip option as a less invasive way to repair your valve? Perhaps this would be a way to hold off OHS for sometime if that is your concern.