When you do pavers on existing patio's they are all thin paver, sand set. this is because of the thresh hold at your back door. This is not unusual. The pavers are going to be mud set on your beam and footers (which will mean you the concrete will be slightly lower) and the deck will be sand set. I do not see a problem, it just might be that you are getting concerned early in the project. Many questions that come up between the builder and owner are premature and are generally solved during the next construction phase. I understand your concerns and it just might be that it was not better defined to you how the process works. As a builder that takes great pride in our customer - builder relationship it might be a good idea to take photos of the process and if you still feel that, down the road, you are having issues then approach a different venue for assistance. In the State of Florida there is a association called the FSPA that not only supports contractors but also pool owners or purchasers. They want to make sure that the industry standards are kept high in this state. Contact them and see if they have any recommendations. From what I see above, the Pool Contractor is not in the wrong and doing exactly what he or she should be doing.