OK, this is what I have "fingered" out. The fuel filter has the regulator attached to it. The fuel filter can be replaced either by itself or as an assembly with the regulator.

Chances are, if the dealer replaced the fuel filter, they did just that and not the regulator also. If you ask they will probably say they do this to save you the cost of unneeded parts (cough, cough). This also adds to the cost in labor they can charge because they have to remove the reg from the old filter, replace the O-rings and install it on the new filter.

From what I can tell from the pictures, if they replaced ANY O-rings this is what they did. To replace the assembly there is only hose clamps.

The parts catalog @ RealOEM.com has both the assembly and just the regulator listed.
Assembly $83.70+core
Regulator $70.30 no core

I found the assembly @ www.autopartswarehouse.com for $62.71 delivered. It's on it's way.

I am determined to find out what is causing this. Stay in tune.