As a normal part of patent examination, you should expect rejections. This is not a certainty, but in almost every case a patent application is rejected on the first examination. This is done with a purpose.
Patent examination is intentionally established as an adversarial process. The patent examiner must advocate for the position that the invention is not patentable. Only when he builds such as case, then is later 'defeated' by careful argument, can we be certain that patentability is fairly established. Where a patent examiner does not make a case against patentability, we can't be so certain the invention should be entitled a patent. Only after a vigorous contest is waged can we come to a sound conclusion. Well, that is how the system is set up to work. Some of you may have comments on whether or not that actually comes about in the real world.
Either way, when you get a first examination back from the USPTO, you should not be alarmed if the examination includes rejections. Your patent counsel will know just what to do. Typically, the arguments to be made will be more of a legal nature than a technical nature. Most inventors are simply incredulous after considering the cited art. The art the examiner cites will sometimes have very little at all in common with the invention. Most unsophisticated inventor will be very upset that an examiner has held his invention 'unpatentable' in view of this previous invention which is nothing at all like that what the application is trying to patent. Again, not to worry. This is quite common and your competent patent attorney will lead you through the process with ease.
Don't become alarmed when you get your first rejections. These will likely go away without too much trouble. If you continue to get rejections on the second and third rounds, this could be a problem. But on the first examination, it is best to just sit back and relax. It is all part of the process.