Nope, no Mandarin in my avatar, but I do currently have three of 'em, and they are the main reason I went from freshwater -> Reef...
Yours is camped out in one particular place? That would be kinda odd... When I added a new one, he would almost immediately go into "grazing" mode, picking stuff off the rocks and wandering around...
Now, having said that, it is common for me to not see any particular one of mine for several days at a time, they'll work their way back into the rockwork and camp out hidden for long stretches of time, but other than when they sleep mine really never sit still in one area...
(When they sleep they'll fade in color and stay in the same place all night. Scared me the first time, I thought she'd died due to the odd change in coloration.)...