Canon 7D AE lock M mode

[LEIGHTON]

I used to be either in shutter priority or aperture priority modes when taking pictures and always use the AE lock button to recompose. Everytime I press the AE lock the * in the viewfinder also lights up. But I recently I decided to switch to Manual Exposure mode. After obtaining the right exposure I press the AE lock but the * in the viewfinder does not light up. Is this normal for M mode? I'm pretty much of a newbie!

Thanks for your inputs!