Yes! I was there on the October tour last year and absolutely felt it near the bottom of those stairs. Dropped several degrees compared to the rest of the corridor, my little K2 meter went mental for about 30 seconds then nothing. My mate thought I was imagining it but she felt it too when she walked through the same spot a minute later.
What gets me is its a consistent thing - loads of people report cold spots in exactly the same location, not just random patches. That feels significant to me. Could be a draught from somewhere obvious, I'm not ruling that out, but the building's been surveyed pretty thoroughly at this point and no one's found a obvious source.
Did you get any readings or was it just physical sensation? Always curious whether the equipment backs it up or not. Some of the best experiences I've had have been ones where the gear picked up absolutely nothing - which almost makes it more interesting in a way.