Prostate Urine Bubble?

Dear All,

I've been having this weird thing with my prostate / urethra for about two months now and I'm wondering if anyone has ever heard of it.  I was diagnosed with nonbacterial prostatitis a few years ago and this comes and goes.  My urologist always prescribes an herbal remedy that seems to work pretty well.

this time it's taken awhile, and although the other prostate symptoms have disappeared this one seems to be lingering.  

Here goes:

After urinating and returning to my seat, or if I'm standing up, and I cross my legs, I get a feeling like a bubble back in my prostate/at the very base (as far as I can tell) of my urethra.  If I "flex" things down there, urine comes out.  I definitely get the feeling that this comes from squeezing my prostate a little by crossing my legs, because if I don't do that, the urine just comes out.

If I "milk" my urethra this doesn't happen - some more comes out, and that's it.  I've always have some more come out into my underwear afterwards, but I've never had this bubble feeling.

No burning while urinating, no increased frequency of urinating, no discharge, no swollen testicles, none of those things.

I know that prostate problems can cause interrupted stream issues, but I don't have that.  Just wondering if anybody has had this?

Also:  I have examined my urine almost religiously, and it all looks normal.