Sometimes (maybe once every 20 times i attempt to charge my MBA), on my MBA 2011, when I connect the magsafe and turn on the power plug, the indicator led does not turn on. On my air battery indicator the status shows "(not charging)", but power source shows: "power sourceower adaptor" is this a hardware/wiring/software/lion/user problem? should i be worried? should i send it to apple care? thank in advance!