OK...just tried to refix this negative. Nothing has changed but I tried also to check level of chemistry in the tank without the lid. With 0.5L reel is fully covered with chemistry. Level of chemistry is actually about 1cm over the reel but...I spotted that there is a possibility of small movements of the reel during processing up and down. In worst case scenario one side of the reel can be even 5mm over the level of chemistry. That would prove your idea guys Matt and Polyglot.
The question is how it is possible. I am processing for over 6 years now. Very often 4-5 times a week...and as I mentioned it happened to me maybe 5 times during last 5 years (2 times in last few days)...ehhh
Thanks a lot!