Couple of my mates have had them and never changed there driving style, you should get a letter through the post about it if they did actually give you one. Section 59's are also for use in towns and areas of anti social behaviour not on the open road as its something like a (public order offence) if you were over taking dangerously it would be a traffic offence of sorts and they would nick you for that. So its probably scare tactics. Wait a week or 2 n see if you get anything through the post, if you are still concerned go to your local police station and ask if theres any offences being held against your car if you are that worried.