Not at all a problem on a domestic flight. I do it all the time. In fact, since the 8/10 rules went into effect, it may make for less hassle, as a "gelcap" won't become an issue unless it is in a bottle that is labeled that way.
The only time I've ever had pill-form meds questioned was when dealing with Customs when entering another country, and that was only because they didn't recognize the pill in question and thought that it might be a controlled substance. Showing them the copy of the scrip took care of the issue. As Sal said, carry copies of your scrips and you will be fine anywhere. (You can get the copies from your pharmacy, either in "duplicate" label form or as a printed list.)
Under the 8/10 rules, Rx liquids or creams must be in Rx labeled containers and declared, which means that you tell the TSA that you have some.