Should you link with your boss on LinkedIn? Yes. It can be great fun.
We all know the signs of the LinkedIn shuffle.
You don't update your profile if everything is going OK.
You tend not to link with half a dozen recruiters in a week for 'fun'.
You don't suddenly get a load of recommendations for no reason.
A devious mind might want to strengthen their position leading up to a review by stacking the odds in their favour.
Update that profile. Accept that request. Have a chat with a few old colleagues about how wonderful you are. Maybe get the wife or girlfriend to call a few times a day for added paranoia.
Enjoy. You never heard it from me.