Thank you everyone - I am glad my instincts proved correct. After the 'incident' we exchanged numbers with the owner - and once the pregnancy was confirmed was when he started to go on and on about having his choice. No stud fee was paid or discussed!
But anyway, no way will I let him take his choice to be sniffed! Being as I have been so fussy about the puppy buyers, do I have the same rights to do this with 'dog man' as I don't know where he lives - just his number??