Q: Follow up to possible ABS wheel speed sensor issues

I had posted here before about my car braking on its own when its wet. My brakes will engage on their own and will remain that way, I will be driving with my foot off the brake pedal and my engine will be fighting agains my brakes to move the car forward. When it dries off, everything will be fine. A mechanic suggested that it was probably the ABS wheel speed sensor being triggered unnecessarily. I just have a few more questions-- there is no light on my dash telling me at any time that there is something wrong with the brakes/ABS, most things I'm reading of people with a similar problem their dash light comes on and mine has not. Also I took it to my dealer and had them inspect the brakes and hook it up to the computer, they said they found absolutely nothing wrong, everything looked normal, and the computer didn't show any alerts. I just had pads replaced, could pads be swelling in the rain or could there be any other culprit?

My car has 144000 miles.
My car has an automatic transmission.