This is an excellent deal for anyone that actually wants one. The market is indeed in a "softening phase", as evidenced by pins sitting unsold at lower prices than we've seen in years. I hope you sell this one soon!
As for warranties, most manufacturers I've worked with have honored the warranty a)past the stated period, and b)beyond the original owner. Having said that, we have to accept we're at the mercy of the manufacturer sometimes. OP: Has the machine been registered? If not, I'd like to think MM would just consider the person opening the box and initially registering the pin as the original owner. It is indeed worth a phone call from a potential buyer.