I would be interested in any insight as to the origins of the name Rosenmann in Germany. Is it some sort of occupational reference, etc?

I am somewhat distantly related to some Rosemans who lived in Rowan County, NC, and from what I have gathered thus far, all of them can be traced back to Germany, in the early 18th century, through Johan Jacob Rosenmann. My grandfather seems to think that it is/was a Jewish name, but he bases that on nothing more than "it sounds Jewish", so I take it with a grain of salt, but thought I might inquire about that as well. Everything I have found so far indicates that they were, in fact, Lutherans. Does anyone have any substantial information on the early (pre-immigration) history of the name?

Thanks in advance.