What curfew ?
Heathrow doesn't have a "curfew", so the question of it being "suspended" doesn't arise.
I suspect what the OP is referring to is the Night Quota, which limits the number of movements between 23:30 and 06:00. For example, during the Summer season (April to October) a maximum total of 3,250 movements is allowed during the Night Quota period.
There is no per-day limit on night flights provided the season limit isn't exceeded (which it never is in summer) and so the fact that there were 9 more flights than normal landing before 06:00 yesterday morning didn't necessitate any relaxation of the restrictions.
Having said that, during periods of severe disruption (including weather-related), Heathrow is allowed to grant dispensations from the night restrictions for small numbers of flights so that they aren't counted against the season's quota.