I would say no, don't kiss him on the lips during the cheek kiss. Let him think you haven't even noticed it...that he's kissing you on the cheek as opposed to the lips. And if he is kissing you on the lips when you ML (which is not TMI, I think we both understand such things! LOL!) that's a good thing I believe.
I say let the cheek thing go, maybe he's waiting for you to react to it. Let it go and make it one of the things you monitor. Wait and see when he kisses you again on the lips.
I think it will be pretty soon.