It's very simple really, when you search for google links, it only displays links that have a certain
PR or better. I'm pretty sure it's 3 or 4. Anything else they don't bother with, if you're taking a look at the people linking to you. If you go to alltheweb, youll get a lot more.
I recently used a program that checks links across several of the major ses. When I checked on one of my sites, goog listed 9 and alltheweb listed the most with 29. These figures will give you a ballpark idea of what I mean.
As far as 3 months goes, I'm not sure I've heard of that one and I'm certain I'vexpirenced anything close to that, that I noticed anyway.
peace...Paul