" Come in, close the door", sounds pretty inviting. It gives the impression you are welcomed in and just you not those others. It makes you feel special. As if you are finally included in a special circle of people who know more than anyone else. Yay you!
Well, here is the problem with the invitation, is this group a part of the focused path you created for yourself? It's great to be invited in, but are the people who are inviting you really in line with your plan for your career. They are managers, maybe a partner or two. They are the people who are decision makers either at a high level or mid-level, but still above you and can put you on some projects that are high visibility. However, are those the projects that are giving you the exposure you want for the career goals that you have? Will being in this circle exclude you from some other circle?
Stay focused! Don't be swayed by an invitation. Sure, be cordial (your mother taught you good manners) but don't allow a momentary acknowledgement to throw you off your path. If this isn't the circle you listed as a goal to become a part of then, take it as a compliment but move on. Every invitation doesn't lead to a good relationship.