Could be a lucky escape; better to be ignored than have one of those slightly-too-long-handshake-whilst-looking-you-straight-in-the-eye moments that some CSDs seem to engage in... or is that just me?
On a flight of mine a few months back, I was very fortunately upgraded to F.
The CSD made a point of meeting all the passengers, and for me, whilst peering over the manifest, announced loudly "Well, that was a nice surprise for you tonight, wasn't it Mr Gaz", leading to a couple of other F passengers looking round to see who the lucky upgrade was.
Now, I'm not one to be ungrateful. But for a few moments, I rather felt like I'd rather be in my my paid J seat where I'd at least not feel singled out in front of the reason of the cabin. If you're going to upgrade me, do it without reminding me how lucky I've been in front of the rest of the cabin. Otherwise, I'd rather be in Club.