Moments of discomfort are not uncommon during specific treatments however your therapist will describe a detailed pain scale that you are encouraged to use throughout treatment. Therapists will check in with you during treatment to make sure they are staying within your tolerable pain threshold.
When you are in pain during a treatment you tend to hold your breath which causes your muscles to tighten and contract which is, usually, counterproductive to your treatment goals. Residual tenderness post treatment can happen but it should not persist past 48 hours. If it does please let your therapist know since that usually means that the treatment was too specific and aggressive. Your therapist can always adjust their treatment style and pressure to your needs and preferences. Remember, communication is key.