ABS issue

ABS activating brake pedal vibrating or pulsating when making u turns or stopping at slow speeds. It’s gradually starting to happen more every day. There is no abs light coming on the dash or anything. I had the front two calipers replaced about two months ago. I also noticed the steering wheel shaking when braking at highway speeds. Maybe a rotor issue? I will have it checked in the next few days. I was just looking for some opinions on the issue I’ve described to see what different areas could be at fault.

Thank you in advance.
Stephen P.