Hi all - yesterday I did an oil change (Valvoline high-mileage) and
replaced the front rotors on my V6 (72,000 mi), something I’d done
several times before on this car and others.  Didn’t have any
difficulties, went very smoothly.  On the way back from my buddy’s
garage where I did the work, I put some regular unleaded in from a
station I’d never used before.  

Very shortly after filling the tank (I’ve checked to make sure the gas
cap is tightened properly), my check engine light came on (and stayed
on after turning it on/off), and the traction control indicator light
came on this morning on the way to work.  It’s not always on when I
start the car, but goes on after a few minutes running;  once it’s on,
it won’t turn off by hitting the manual TCS switch, even on bone-dry
roads.  

I have a couple questions that I’m hoping someone could answer for me
(checked the forum and didn’t find any topics like this one) before I
go take it up the arse to get this fixed:

a)  Can a rotor replacement screw with the TCS sensors (bearing in
mind I’ve done this before and never had problems)?
b)  Is there a chance that this TCS problem could make the computer
throw up a code to check engine?
c)  Should I try a hard reset of the computer by removing the negative
battery connection for a few minutes and see if the problem reappears?

Obviously I’ve considered that this may all be a coincidence, but I’ve
never had any of these issues in the 65k mi that I’ve owned the car
for, so for them all to occur within a day of doing the maintenance
makes me wonder.  Thanks in advance for any help.