Pain In Urethra From Stretching (Upwards?)

I have just recently started vacuum-stretching and the stretch feels amazing. After a half year of trying all kinds of stretchers, the vacuum stretcher takes the win for my uncut penis.

The thing is.. I tried to stretch yesterday after 3 days of stretching and to my amazement, it was the urethra that was fatigued (and even hurts!) when stretched.
A couple of days ago I coincidentally thought to myself that through stretching, the urethra must grow as well with the rest of the lot.

My question: has anybody ever heard of this kind of case? Is it ‘normal’?