oil pan and oxegen

Hello
I have a 99 Taurus and just had the oil pan replaced. The next morning after picking it up the "check engine" light was on. I took it back to the shop and they now say the oxegen sensor on the muffler needs to be replaced. Could this have been disturbed when they took out the muffler to get to the oil pan?
I dropped 600.00 for the oil pan....ahhhh
thanks for any replies.

No, not unless they forgot to plug it back up or routed the wires so that they got burned on the exhaust... take it to another shop. O2 sensor replacement shouldn't cost more than 60 bucks, and it seems as if they are ripping you off anyway after charging 600 for a 200 job...

They could have loosened up some crud in the pipes and that may have gotten in the sensor. If you've never replaced the sensors it's not a bad (or hard) thing to do. About 50 bucks each sounds right for the sensors.

Thanks for the information. It rained out a bit last night...not that the rain did anything, but the check engine light went off. I have to bring the car in for a recall, so I will have them look at it.....
thanks again