He can't help but straighten up a little under that gaze (as if he didn't already have pretty great posture, but there's always room to do anything better, as far as Leo's concerned). It feels a little like being appraised by Master Splinter, albeit with a little more distance, but even with that it's more than enough to make him feel like this guy ought to be taken more seriously.

"I wasn't expecting to get better by doing nothing."