No, +30 isn't all that crazy, for a skill-monkey's specialty skill. But it's what that +30 meant that was setting off alarms.
Of course, +30 is kind of insane for a 15th level character, if that character isn't a skill monkey and/or hasn't focused on a particular skill.
Consider a typical Fighter, Sorcerer, Cleric etc: Intelligence isn't a stat you necessarily pump, and you get two points per level. If you've made Int a dump stat, as many fighter types do, you get 1 per level.
In that situation, you're looking at spending half of all your Skill points (or more), throughout an entire career, on one skill, spending the rest on Synergy skills, and then dedicating Feats and magic item picks on top of that, to get the rest of that +30.
That skill would be pretty much the only thing you're any good at at all.
So, in that sense, +30 would require a certain amount of "crazy" to get.