Had the Akebono BBK installed a few weeks back on my 07 G35 Sedan. Got the calipers on ebay with 40K miles and they appeared to be in good condition. Had the car at the dealership over the weekend for an oil change and they advised that one of the calipers was leaking fluid and I should replace right away.
Looking at the inside center portion of the rim it is lightly coated break fluid. I can also feel the residue from the fluid on the very bottom portion of the caliper. I haven't noticed any performance issues and the car seems to break normally.
Would this mean the caliper needs to be rebuilt or could this just be a bad connection to break line? I had a for-hire mobile mechanic do the install so I am not very knowledgeable on what this could be.

 

I'm no expert but I guess it can be both. Maybe you should take the wheel out and see if you can find the source of the leak?

 

Buy the rebuild kit for 40 bucks or so and have a brake shop install it..problem solved, easy fix

 

The leak can come from anywhere... the lines/hoses, piston seals or even the caliper itself (i.e. if someone opened it up before and didn't put it together properly.)

I recommend you take the time out to inspect everything from point a to z. It could be stopping fine now, but if you're leaking, there's a good chance air has also been introduced into the system. Air compresses more readily than brake fluid. When push comes to shove (emergency braking) your car won't stop as expected.

p.s. If you're leaking fluid and it's getting on your wheels, it's only a matter of time before it'll start eating into the wheel paint. It may also have already been in contact with other painted parts of the car.