TL;DR We had it under control, but we are losing control. So we need to take action now (limit importation of new cases and new local spread) before a new lockdown is needed. Hence the holiday (from social distancing measures) is over.

The problem is that Norwegians have essentially had a vacation from worrying about Covid, since there has been more or less no new cases since May-June. This has made the Norwegian population more relaxed, meaning more social gatherings have been taking place, bars have reopened, etc.

However, during the summer months there was some tourism to and from other European countries, which seems to have caused a potential new outbreak of Covid.

So, when the health minister says "I think most of us have now understood the holiday is over" he means that it is time to start thinking about social distancing, thinking about work-from-home policies and your personal hygiene again.