Yes, they might, but in 30+ years of travel, I've never seen it...and I've brought a LOT of un-registered guests into a LOT of lounges. Act like you're supposed to be there, don't ask stupid questions like 'can I bring my friend who isn't staying in my room in?' and you're probably fine. The most stringent scrutiny I've ever been given is 'what's your room # Sir?', which they then check against a list to see if that room is eligible for breakfast, lounge access, whatever and we move on from there...easy peasy!