Kind of. People are generally good at adapting to subtle/gradual changes, so I was never really alarmed before the CEL came on. However, there were a few things I noticed. I'm not sure I'd call it hesitation, but the car felt like it was a little low on power-kind of like with a slightly rubbing brake pad or overly high viscosity oil (drag). The idle felt different too. My car vibrates at low rpm anyway, but it was also inconsistent and rough. The first thing I noticed after I cleaned the MAF, was that the car would start up instantly. It wasn't bad before, but it would sometimes take a second or two to fire up. It also wasn't idling up on cold start and now it does.@Jonas - did you have any drivability issues with the dirty MAF or was the only reason you noticed was from the CEL? All the GM 3800's I have/had get a bit of hesitation when they start getting dirty, long before the CEL comes on.