As long as you carry a copy of the I-485 receipt with you to prove that your AOS is still actually pending, and you are not otherwise ineligible to reenter the US (e.g. you have previously accumulated too many days of unlawful presence), you should be okay. If you are the primary AOS applicant, it's safer to have your EAD with you in case asked how you support yourself in the US. If you want to be extra cautious, carry a letter from your employer. But no, you should have no problem with AP unless (as I mentioned) you are ineligible to enter for some other reason.
