Question about TH350

[JDaw]

I need some help with my trans.
New th350 purchased from jegs, but made by B&M. I dont drive it often, maybe once a week at most. Ive noticed over the last few months that it has been doing this weird issue where when I first start it up. It will not go into any gear. I let it idle for sometimes up to a five to ten minutes and then it will go in reverse or drive and operate as usual. Ive finally gotten around to trying to tackle the problem. When I contacted B&M they say that it is an issue with a stuck valve that is allowing the torque converted to empty itself when it sits and recommend I drive it more frequently to help un-stick the valve. Does this sound right? I have checked fluids and they are all adequate. Anything else I can check? Of course it is out of warranty so Im a big fan of the "it will fix itself" answer, if that is in fact the case.

Thanks