Nope. It's just moving into the target's square and making opposed Athletics checks. Size in grappling is getting the hairy eyeball. Alex and I will work something out before the first errata update hits (and no, it's not coming imminently, though "soon-ish" is probably within reason).
Requiring a full-round unarmed attack check, whose effect is initiating a Grapple (i.e. the attack wouldn't do damage), seems an easy way to give smaller characters a shot at avoiding this particular fate. Grapple is already an attack action, so this isn't much of a conceptual leap and doesn't generate a bunch of messy rule interactions (they're already present). And, the attack + Athletics combo is no more complicated than the typical two attack rolls the player might otherwise be making in a standard round of combat. Plus, it preserves the concept that the smaller opponent needs to avoid the grasp of the larger.