JaVale McGee Has 'No Idea' Why LeBron Blocked Him On Instagram

[[tmz:video id="0_5iqw7hgd"]] LeBron James finally unblocked his new Lakers teammate, JaVale McGee, on Instagram this week ... so, when we saw JM at LAX, we had to ask ... WHY!? Turns out, the whole thing dates back 5 years ... but JaVale tells TMZ…