Given that your cardiologist recommended you follow up I would have to advise the same. Your pressure reading is borderline high. It may have been an incidental thing that has since resolved but it is safest to be sure.
I would recommend you readdress this issue with your doctor and see what his reasoning for not needing the follow up is. There may be a very good reason.
Advice and opinions given are based on the information provided and must not be considered an official medical recommendation. The limitations of the internet prevent an appropriate evaluation. Always consult your doctor if there is concern.