Heimer turrets and Mordekaiser

This is the first time I have ever been in this matchup and I don't know if this is necessarily a bug but to me seems like a possible coding error. I consistently was getting Mordekaiser down under half HP and he would kill 1 turret and heal up to almost full HP instantly. From the other players explanation after the match that the turrets are considered jungle monsters basically? If this is in fact the case this all seems a bit broken. I get this matchup in extremely rare as very few people play mordekaiser any more but I'm a bit curious if this is infact a bug?