I'd be deeply concerned if they didn't. The entire scientific method depends on the proposal, exploration, testing, and validation of hypotheses, out of which theories are constructed and consensus reached.
As we learn more over time, theories are tested, found wanting, and discarded or used for only a restricted set of conditions - the perfect example being Newtonian mechanics. Inadequate to explain all conditions but still useful for most. Our knowledge and understanding is changing all the time, there are no immutable truths - save possibly the laws of Mathematics.
I'm constantly surprised by people's failure to understand how science works, but sadly I'm not in the least bit surprised by the willingness of politicians to declare that they are 'following the science' when in fact they are doing no such thing at all.
