Wasn't there myself but a mate of mine did that tour about three weeks back and said the same thing - this weird pressure feeling on the fifth floor, like something was just standing behind him the whole time. He's not easily spooked either, bloke's done Pendle Hill twice without batting an eye.
What exactly did you feel? Was it a physical thing or more like a mood shift, that heavy atmosphere type deal? I've read loads of accounts from Waverly and the fifth floor comes up constantly which is interesting because thats supposed to be where a lot of the TB patients were kept isolated.
Really gutted I couldn't make the trip over, been wanting to do Waverly for years. Would love to hear more details from anyone else who was on that tour.