At the end of the day you had the courtesy to reference your sources. You stated what you were doing, you have not ripped off his guitar.
If worst came to worse and they could do something, you would be told "Ether stop/don't sell the guitar or you will go to court and here is full proof" not idle "Hey! You copied me!" Playground talk.
I wouldn't change it tbh, just stand your ground. You make truly wonderful instruments, it's just professional jealousy. At the end of the day, your reference your sources and don't seek to rip things off, enough aspects are different from that guitar and if I recall, on yourse you had the idea of integrating the curve into the headstock (if this wasn't on "Moser the pousers" original, if it was then I'll shut up now )
So, ultimately don't get too stressed. A little bit of friendly dialogue would be good, to try to calm the guy down, but be warned that he is protecting his financial intrests first, not necessarily with anything he can back up. So, take what he says with a pinch of salt. Keep posting back here, as the advice of many is better than that of few.
EDIT: Small little question, how did you do your mirror top? Their literally stick a mirror to the top of the guitar it seems, but how did you work it, get it to shape and what did you glue it down with? I'd love to try something similar myself- just don't sue me!