I think you are right about the tobacco, it must be imported from other growers. Although not from Cuba, they wouldn't be allowed to sell in the US if that was the case.
I'm sure your friend knew what he was talking about, Don Benigno cigars seem to be very popular in the UK and South America.
What you say about the cigars you smoked with him is normal for beginner smokers. Either they are good, or they are not. Why they taste good to you is hard to figure out at the beginning, until you gain experience and smoke a lot of different kinds. Then you start to enjoy and discern certain aspects about a cigar, and pick up subtle nuances that make up the blend. All that is just icing on the cake, the cake is a great cigar. Unless its stale moldy cake ;-P