2006 Rear Window Beginning to Rust

Hello everyone,
I am new here and have a 2006 Tundra Access Cab. I just washed the truck today and noticed a little rust streak running down from behind the rear window seal/plastic. I have had this truck for about a year and a half and i love it! I am meticulous about caring for it so noticing this really raised some concerns for me. I poked around the steal a little to see if it was loose or coming off. It did not appear compromised but and i was able to get about a teaspoon of water to drop down from behind it when i peeled it up slightly. I already checked the rear brake light housing and it is dry, so I'm just looking for any other things to check. Since it is a rust problem i am probably going to have to take it to a body shop to get it repaired correctly. Thank you in advance for any information!

 

have the same streaks same spot on my 03...

 

I saw way less and when the shop pulled the weather stripping, it was a mess. Take care of it asap. I'm down $1600

 

thank you for the reply, thats a bummer tho. I will definitely get it in to get fixed as soon as i can. Do you have any idea what the culprit is for this problem? Id hate to get it fixed only for it to happen again. I looked at the roof seals along the rood and they dont look bad, the driver side one (other side than rust) is starting to peel up from the rear. I wonder if this has anything to do with this.