You questioned about the air just after the humidifier being more then 45% for the purpose of questioning whether mold will be active at that point. The answer was "no", not that I have ever seen. With the air movement at the return temperatures, there is little concern about the relative humidity level between the humidifier and the blower dropping below dewpoint in order to condense the moisture in the air at that point.Since mold requires moisture, there is little chance of mold forming between the humidifier and the blower. I will never say never because I suppose there can always be conditions that could cause this issue, but I have never seen this issue in the over 40 years I have been involved in HVAC.