He's not saying that the points just disappeared.
When someone is in a dangerous province, and is attacked while digging, they lose the action points (and potentially resources and gold).
What happened to Gunner is that he hadn't started digging, but had only setup the dig - he had NOT clicked the 'dig' button yet - and was attacked. The system read the current dig setup that he was looking at and assumed it was active and took his 15 AP. The reason this may not have happened to anyone else is because there is probably only 1 or 2 seconds between setting up the dig and actually starting the dig - for most people. Gunner got distracted and hadn't started the dig. The system nonetheless read his status as digging and took the AP.