Hi everyone,
Following from @Slant_Eng 's advice above, I did blow dry air from hair dryer directly to the sensor (5-10 cm away), as it was attached to my nodemcu (soldered), and it fixed it! 
The dht22 was showing 99.90% humidity for over two weeks (worked fine before that and temperature is accurate) and I have already replaced one sensor for the same reason some months ago. I am now thinking that I should not have... hair dryer is a solution!
Thanks @Slant_Eng and all other related input on the matter!
Together we will prevail :o
PS: unfortunately not fixed... See the data after heating up the sensor and letting it cool down below.
|t = 25.94C |h = 99.90%
|t = 62.41C |h = 43.80%
|t = 52.10C |h = 45.70%
|t = 48.65C |h = 50.60%
|t = 48.48C |h = 57.20%
|t = 44.52C |h = 59.50%
|t = 42.63C |h = 67.30%
|t = 42.00C |h = 74.20%
|t = 41.75C |h = 78.70%
|t = 41.15C |h = 83.70%
|t = 40.95C |h = 96.20%
|t = 35.99C |h = 99.90%