Just about every crank seal will eventually leak, some go earlier than others. Its not a major problem unless you dont like a dirty undercarriage. And considering that they are tough to change, especially the rear seal which means taking the trans out, they are rarely ever changed and the engines work fine anyways, just dirtier.
BTW a TSB is a technical service bulletin is just a set of instructions clarifying a repair, a new way to perform a repair, or just a list of approved shortcuts to make the mechanics life easier. They're like updates to the official shop manuals. With or without warranty, your mechanic will use these (if he has access to them). If your car is under warranty, there will usually be no charge.
A recall is for a major safety problem, and will likely contain TSB-style information in order to perform the repairs. Thinks like leaking fuel lines or major engine problems can lead to recalls since they pose a safety danger, or a major danger to the company's image!
Hope that clears it up some, the two terms are not interchangeable, lol! There may be a TSB for a new type of crank seal, but it wouldnt be and cant be called a recall. I've had two TSB's done on my Impala under warranty, one was for the intake manifold gaskets, the other for a bad cat converter. The TSB's spelled out how to verify the problem and what new parts to use and procedures to perform.