This. If your position and pay don't warrant you worrying about, report it and don't worry about it.
While I originally wanted to also agree with this portion, it's kind of presumptuous. One person claims they saw a gun in a waistband without a holster. Could it not have been in an IWB holster?
http://cdn.aliengearholsters.com/media/catalog/product/cache/1/image/1200x/040ec09b1e35df139433887a97daa66f/c/o/concealed-carry-revolver-holster_1_3.jpg
http://www.holsterhero.com/wp-content/uploads/2014/10/Iwb-holster-open.jpg
Back to agreeing with Kerry.
All that being said, depending on the firearm, holster or not, etc, the member maybe, possibly, might have, accidentally forgotten. Yeah, swinging clubs all day you'd think you'd remember/notice, but if he carries all day errday...
Also, we're assuming the golfer is NOT off duty LEO.
Judgement based off assumptions of one persons observations as they remember them happening awhile later. 'Murica.
I'm not saying yes/no, right/wrong. I'm saying I agree with Kerry that it should be reported to the proper person of authority at the country club. Hell, they may know the individual and the situation. I dunno.