Kindreds Passive?

I'm not sure if anyone else has experienced this, but while playing ARAM I noticed Kindred's passive was bugging. I had marked Moakai, either killed him or got an assist I can't remember. But after I got the point in my mark, there was no cool down time on when I could mark him again. I was able to mark him again immediately after. This also happened to me the same game with Cassiopeia. And again in another game I played last night. Anyone else experience this?