Sean, there's a chance that the reason has to do with how stable/unstable you are on the bike.
It's clear that if you are not managing to get yourself "locked-on" securely i.e. without holding onto the bars like your life depended upon it, the feeling of insecurity WILL increase with lean angle.
Can you put the bike onto paddock stands (or get some strong mates to hold it upright) and get yourself into your normal cornering body position to see exactly how you lock-on? See TOTW2 for a list of possible points to anchor yourself onto the bike. You should be able to release your grip on the bars (or even let go altogether) without falling off!
If you know that there's no chance of you and the bike parting company once you lean it over, you can then rely on using your knee slider as a lean angle gauge.
Good luck,
David