I wouldn't be worked about RI at all, the parts of Africa that BP's come from averages humidity levels between 65% - 80% year round...
As long as there isn't condensation on the tubs you should be fine. Do keep an eye out for mold growth, I wouldn't expect any issues at humidity levels in the upper 60's, but it is always possible.
My PVC cages stay at 60% (in the entire cage) all the time with no issues. I boost the humidity up to 70% during shed.
*EDIT*
I don't mean to imply that the OP shouldn't read up on RI, that is a very important thing to know regardless... All I was saying is that from my experience I would say that the OP shouldn't have any issues.