An Unexpected publication??

[Dylan & Marianne]

Through flickr, America's Popular Photography magazine found one of my pictures and paid me for use of the following picture in their April magazine as part of a travel special. That was all fine but then, my friend in Iceland has recently let me know that a local newspaper has since used that picture as well?

My first reaction was "Cool, I got published in Iceland!" but then , on reflection, why wasn't I notified? I'm not upset, just curious to know what people think about the legalities of photographing a magazine picture for their own publication.
<Edit> Actually, after figuring out the page, the link was to pop photography's website with the appropriate credit and all so I guess it's all good!

This is the link and the picture
25 best places to photograph