@ctilley79 it's because the data was inconsistent that it took so long - it ran for the maximum 25 cycles (the minimum is 5). Inconsistent data can be caused by noise in the temperature reading, or by a change in the ambient temperature as the tuning is being done - for example, if the printer is enclosed and the bed is heating the machine and its chamber.
As @jay_s_uk says, use the values it reported despite the warning.