Firstly - Congratulations!
I have made almost all the long term partners I've had squirt. Some from day one some later on.
What I've realized is that most women can do it when they cum properly. I mean that when you hit their G-Spot and are about to cum they get the urge to wee (as explained by a GF). Many women stop at this point and don't get a full climax.
If you can get them past this stage, I've had some cum many times in a row! (women are so lucky)
Sounds like your mrs has gone past this barrier (not your fault) but with your help. An ex told me she never used to do this during sex as she knew she would wet the bed so always stopped. After I was comfortable with it, god did she squirt. Made me so horny everytime. Also was great having such a wet pussy.
Enjoy!
Lastly - Hunter - It's not pee. I've been licking a gals pussy once and she squirted all over my face. And I can tell you its a different brew.