That does highlight one of the usual issues with gargoyles, though - usually nobody's fooled by them. One mention of statues in a location description and the players are just waiting for them to come to life (or turn out to be medusa victims). It rather ruins the "ambush" part of their ambush predators vibe.
Maybe find some alternate hiding options for them to deal with that? Like, maybe there's a subspecies that can flatten themselves out and become bas-relief carvings on a wall, or one that can look decrepit and broken-down to allay suspicions.