strength of age mastery

so i just played my first game with new masteries and i had a strength of ages mastery on my jungler. i hit the full 300 hp that i was allowed to get but after you cap out if you kill a jungle or large minion your supposed to get 100 health back as well. that didnt happen or if it did it gave me health back like a health potion, anyone knows if its supposed to be like instant 100 hp or slow 100 hp?