2007 xc90 v6. Possible Transmission problems

Hi Volvo Lovers,

Right now i'm feeling guilty and i'm hoping that it isn't a transmission issue. A little back story I bought a used 2002 Volvo s60 and I love the car, it has 183k miles and still going strong. For awhile I had some transmission problems slipping, weird shifting ect. I got my cat converter manifold replaced and the problems pretty much went away, it performs way better.

This is where the the xc90 comes in. My mom was in the market for a car and she owned a couple p1800s back in the 70s, a volvo wagon in the 90s. She was looking at a few SUVs (Cadillac, Volvo xc90, and hyundia Tucson). I of course told her to go with the Volvo, but after doing research on the car I noticed that 2002-2007 models have had some transmission issues (I told her this but she went ahead with the purchase anyways). I told her right away to get the extended warranty, but she didn't because it was 4k. The car is in beautiful condition it only has 77k miles on it.

I took the car for a spin and noticed the engine was making some weird noise, so I told her to get it checked out. The local Volvo dealership said that she needed a new transmission. Is it just me or does getting a new transmission at 77k miles seem insane? I have a mechanic that I trust and told her I wouldn't believe the dealership and she should have my mechanic check it out and get a second opinion. The thing is when I took it for a spin and noticed the weird noise the shifting, acceleration seemed fine (thats why i'm questioning the dealerships diagnosis). She hasn't even had this car for a year yet, so it would be a huge disappointment if it was the transmission, I know how expensive it would be to get it replaced. Any thoughts or comments would be much appreciated.