Heh........70 is not a bad humidity, its actually perfect.

Keeping a better eye on it would be my only suggestion. You say its 60-70 all the time, how many times a day do you really check it? Humidity can fluctuate quite rapidly. Unstable humidity is the better diagnosis I believe.

Bad sheds are not really THAT bad, as long as all of the shed is off. Sometimes a lil help is needed .