Tranny Problem

[lukecp]

I have been having a problem with the TH350 in my truck for the last couple days. After the truck has sat for an hour or two, and i go to start it up, when i try to put it in either drive or reverse, i will move the shifter to the gear, but it won't go in to either gear. The tranny will stay in park, but it wont engage. Then, about 10-15 seconds later, it will go into gear just fine. The tranny was rebuilt 3 months ago. When it does go in, it shifts nice and firm, and has zero other problems. When it is warm or when i drive it in the morning, it is just fine. I called the tranny shop where the tranny came from (Ace Trannsmission in Springfield, MO) they said that it was proably having some toruqe converter drainback, and that they would install a one-way check valve on the tranny, and that it should fix it. They said that it wouldn't cost anything. Does this sound like the problem that is making it not want to go into gear?