2003 GMC Envoy leaking from rear end and transfer case

I recently had my Envoy repaired at the dealer ship because of a recall to the fuel sending unit above the gas tank. Now I noticed oil is coming out of the rear end and transfer case. Wondering if the technition could of uninstalled the drive shaft to drop the gas tank causing the rear end and tansfer case to leak. It is just really wierd for both of transfer case and rear end to leak like that.