Wheel Axle Bearing?

I took my 1997 Mustang (yeah, the green one with the pink stripes) to  Pepboys on Wed evening for an oil change ($19.95 coupon).  The tech said there was a leak in the right rear axle and I needed to have the bearing replaced, etc.  He wasn't bs'ing me as I made him take me under the car and show me.   This problem must have come up since March when I had the brakes done so that gives you the time frame of how long I've driven the car on the outside (March until now) potentially with the problem.  I haven't noticed any noise, vibration, etc.  Simply, there is a leak. My "mechanic" hasn't returned my call. I'm worried. I can't do the repair until mid-October.  Pepboys said I can add fluid. Where? How difficult is this to do?  

Just a girl and her car...

Is it the bearing that is bad or just the seal? You add fluid to the differential. There is a drain and a fill plug. Did they check the fluid lever when they did the oil change? They should have and topped it off for you. Was it just damp around the area or really wet?

A bit of a drip around the brake line. Top it off? He wanted to sell me a transmission service.

Yeah, top off the diff fluid. Since the axle seal is leaking, the next step any competent mechanic would do is check the fluid to see if and how low it is. 

Not a fan of Pep boys type mocanincs. May wanna look for someone more reliable.

I just changed my bearings and seals. It's not a bad job. Adding fluid is a pain on the mustang.
Seals go bad. It happens. I replaced the 2 outer bearings and seals along with fluid for $98. It would have been double for parts from Ford plus the labor.
I'm around for another 5 weeks so shoot me a message if you need assistance and we can meet up some time.