It's essential to prioritize your feelings and emotional well-being in any situation, including this one. Feeling violated and uncomfortable when someone touches you without consent is a valid reaction. If you didn't feel comfortable discussing the marks at that moment, it was entirely within your rights to pull your arm back and express that you didn't want to talk about it.
Whether or not to further address the situation depends on your own feelings and comfort level. If you trust and feel safe with your friend, you might consider discussing how their grabbing your arm made you feel and why it was inappropriate for them to do so without consent. Honest communication can help resolve misunderstandings and improve your friendship.
However, if you do not feel comfortable discussing the matter with your friend or if the behavior continues, it might be helpful to seek support from someone you trust, such as another friend, family member, or a professional counselor. They can provide a safe space to talk about your feelings and offer guidance on how to handle the situation.
Remember, setting boundaries and respecting personal space are essential aspects of any healthy relationship. Your feelings and boundaries should be respected by those around you.