I'm a piano tuner in the mid Atlantic. If the piano was dry, adding humidity will affect the tuning. The most noticable of the change will be the low tenor, crossing over to the bass bridge. In this area, 5ths and octaves go wonky first in a humidity change. The ends of the piano are the most stable, but we reference everything in our mind from the middle. The piano will go sharp from the additional humidity, mostly in the middle. Give it 2-3 weeks to settle down and the next tuning will hold much better.