A question for our traffic police members

Is it common for traffic police to drive level with/drive behind/generally hang around somebody whom may have done something that could be seen as naughty/silly to make their presence known as a bit of a warning sort of thing and whilst they check the NPC? I ask as a friend had this happen this morning and is a little worried they'll receive an NIP. The friend wasn't tugged.

Thanks in advance.

[Red Herring]

Yes, not only does it take a moment for all the relevant checks to come back (it's PNC) but as you say a good eyeball can often say as much as a few words....and what exactly had your mate done?