He's definately not thinking about it at all in a sexual way. It is like Adult Mikuru showing Kyon her mole (on her breasts) without thinking about it in the slightest.
She showed some cleavage--she didn't take her shirt off. And there's a big difference between future!Mikuru and present!Mikuru. Do recall present!Mikuru's reaction when Kyon mentioned the mole.
Of all things, why did I have to be born hung like a horse?Because, look...Uwah!I've done a bit of research and given things some thought...So let me say just one thing:Kyonko-chan... Actually, I share your pain.Kyonko's True Intentions 3Why am I flat-chested?