Nocturne Passive Bug

So I was playing Nocturne in the jg and I was noticing that my passive was being used even though I hadn't attacked anything in a while. Later on I tested it and my passive was being activated on plants. I am not sure if this is a bug or no, but it seems stupid that I am gonna heal for like 10 hp off a plant instead of having an easier time with the raptors.

Thanks in advance.