Not that odd then. I never pushed my DC's to the next stage, but they each moved on when it was the right time for them.
DS3 was moved out of a cot and highchair far earlier than I would have liked, but it was purely for safety reasons. You can't tie him down or hem him in! He sits perfectly well on a dining chair, and has done since we got rid of the highchair.
I suspect that that is because he knows that he can get down, should he want to, yet in a highchair, the straps seem to instantly say to him that he can't get down.
He's the same with his bed - if I had known sooner that the reason he NEVER slept in it, and either co slept or climbed out to co sleep was because he detested the 'hemmed in' feeling of the bars, I would gave put him in a bed sooner!
From his first night in his bed, he doesn't get out of it until he wakes in the morning.
Contrary bugger, my DS3! 
I reckon he will be slightly claustrophobic tbh. Never felt the need to test this yet...