Ok, I think i found something relevant. From:
http://www.cheesetique.com/Newslette...Newsletter.htm
"Gouda when it's young is an ideal melting cheese. When extra-aged (like out 4-year Beemster) it is intense in flavor and quite crumbly....A harder gouda might not melt as well - better to stick with a mid-aged one."
So it's possible that your gouda was smoked and aged as well, or the smoking process hardens it like aging does. ::shrugs::