Depends on how the humidity is being achieved. Natural humidity outside or the relative humidity that is inside your house normal then no. If the enclousure is staying drenched through misting sessions or a humidifier that is running all the time then possibly. This is just in relation to the dangers that come with standing water of any type. Some groups of veileds are native on the southwestern side of mountains in Yemen that recieves 80" of rain a year. This climate is similar to that of a jackson or other montane species. This is an extreme humidity type climate so I would not worry about it with veileds. Just make sure it is safe humidity.
Just not exposing them to a lot of standing water in an effort to keep the humidity in the cage. Nooks and cranies of the cage that are constantly saturated without allowing to dry out can promote bacterial growth. With the what you are talking about is fine. The humidity in my house stays around 70% most of the year. This just leaves my one less concern with housing them.
You have to think...in madagascar im sure at times of rain it would easily reach over 90% for short times so im sure any chameleon would thrive if humidity got over 60% from time to time. When i run my misting system it gets to about 80% for a short time. then goes down to about 65-70 for most of the day.