Anyone had irregular bleeding after using Norethisterone

I took Norethisterone from the 20th July until the 3rd August to delay a period for a holiday and it worked well while I was using it… my period arrived 3 days after stopping.

I then had what I think was another period last week but I was in agony with cramps few days before and it was very light.

On 2 occasions I have bled after sex since stopping the Norethisterone…only slightly …including last night even though my period had finished?

Is this a normal side effect after stopping Norethisterone or is it cause for concern?

I have never bled after sex before?