When I was looking at building in 2001, we were driven to a unfinished home and given a tour by the sales person of a boutique builder.
Hi Izzysyd
It must b due to W H not having any showhouse for narrow lot of the layout you have. Happens tat the prospective customer wants same layout, and yours got to b a display house for a few hours.
but if I'm in your shoes, I'll complain all the way to the builder big boss as no permission was asked at all. probably squeeze some more stuff from the builder who will benefit from showing others around your hse.