"Accelerate" on the cruise is slowing car...?

[spacy9]

I'm going to take the car into the shop for this but I was wondering if anyone has experienced this before and what it turned out to be.

I was driving through the mountains yesterday and after the cruise was set at say 55 and I hit the "Resume/Accelerate" switch the car would slow down 1 MPH each time I hit it. I turned the cruise off and on several times and it kept the same behavior. I tried pushing the "Coast/Set" switch and it slowed me down as well.

I thought maybe it was just a glitch and tried it on the return trip after the car had sat for a couple of hours and it still has the same behavior.

It's just weird. And this was just the normal cruise, not the radar controlled.

Thanks for any insight into this one.