To answer your question - I think that would be dependent on the person. For me - I would not be offended. Just like I am not offended when out to a business dinner and people order wine, beer, etc. I think most Mormons would feel the same way, but I guess there might be some that could be. For those Mormons that live outside of Utah, SE Idaho - we are used to our friends drinking wine/beer at dinner. I think it could be uncomfortable for most mormons if heavy drinking of alcohol happened to the point that people are getting noticeably drunk.  
 
Hope that helps. 
 
Thanks

It shouldn't be but you never know, each person has different levels of offense. I would suggest if you feel that they would be uncomfortable around people drinking wine for any reason to let them know when you extend the invitation that way they are aware when they make there decision.  
 
For all you know they could of once had drinking problems or gave up alcohol when they joined the Church and would take offense to have alcohol around there children at a kids birthday party.