Yes, this is normal. After salpingectomy for ectopic pregnancy, periods can return as early as 3 weeks, especially since your hCG level was low (~500) at surgery.
Brown discharge with mild pelvic pain usually indicates that periods are about to start.
Next Steps
If bleeding becomes heavy, pain worsens, or symptoms persist, please consult.
Health Tips
As long as there is no fever, severe pain, foul-smelling discharge, or heavy bleeding, this is likely due to hormonal adjustment after surgery and not a complication.