No, sausagehead, you are not a freak. I see this phenomenon everyday. The best performance was this guy who squirted saliva from the floor of the mouth (the anatomical name) onto his forehead whilst lying in my dental chair. It was truly amazing! I was glad I gave him safety glass, else he would've thought I was a lousy dentist spraying stuff everywhere...
They always remind me of cunjevois, native Australian sea squirts that are found along our southern Australian coast line. They just squirt out water just like the salivary glands under your tongue. I reckon they spray up to 1 m high!
But I digress.
I have found that I personally get a squirt or two when I yawn. I can only surmise that the muscular contraction of the floor of the mouth changes the interstitial pressures and squeezes the gland(s) and hence the squirt of saliva. But then, my patients seem to squirt them indiscriminately.
Of course, alex.tan is correct in saying that you can stimulate salivary flow by placing a drop of lemon juice or vinegar - but not over the gland - on the tip of the tongue. This is actually a good test to see if there is any obstruction of the duct. See sialolithiasis.
And it is probably not only the sublingual gland that is relevant in this case. In fact, submandibular gland duct opens very near the sublingual gland, despite the gland being further back in the mouth. Being the larger gland, I reckon it has a bigger role to play. And notwithstanding the fact that the main duct of the sublingual gland sometimes even opens into the submandibular gland duct aka Wharton's duct, if not just beside it.
Just to clarify, the sublingual gland tends to have a main larger duct (Bartholin's duct) and a few smaller ones. All the above mention ducts open more-or-less into the floor of the mouth i.e. under the tongue.