What is De-nibbing??

[FOT Fast]

I picked up a car from an insurance approved repairer tonight. I had a good look in the dark at the area they had repaired and noticed a very small raised bump on the paintwork.

I then went and got the guy to have a look and he said "Oh it just needs de-nibbing. I'll do it now!"

Off he went for 5mins and then it was gone?!

What is De-nibbing in paintworking terms?? It's not something I've heard of before.....

Thanks

[PJ S]

Removal of bits of trapped dust or other foreign material that form imperfections in painted or varnished surfaces.