I see what the problem is. My check has a “automatic” lower threshold if nothing is defined from 20% of maximum speed.
In your case this would be 4280 rpm as lower threshold. Your fan has only 4116 rpm.
To fix this problem you can edit the file.
lenovo_xclarity_fans.py
Line 50
min_warn = max_range / 100 * 20
to
min_warn = max_range / 100 * 10
This is only a quick workaround. I need to implement the possibility to define own thresholds from setup.