A few days ago I got a security warning on one NGA page but unfortunately I can't remember which one. It wasn't the Adenium one. If it happens again I'll make a more useful report than this one!
I just wanted to say, as an aside, that it's interesting to see the country differences. It sounds like in the US you are getting NGA within the first few Google results on the first page. When I Google "garden" here it automatically sends me to the Canadian site, google.ca, and on that NGA doesn't come up until the seventh page of results!