Actually, you probably have; it’s just a bit harder to notice a clitoral erection than a penile one. Morning wood seems to be most strongly related to REM sleep, which is generally what you’ll experience before waking up as long as your sleeping patterns are normal.
Huh. Cool. Thanks, ultrafilter.
FWIW:
The article goes on to say there is little evidence to support the connection between the need to urinate and night time erection.
On a personal note: I’m more of a morning person when I can make use of my wood.
Well, physicians that deal with impotence do often use the “morning wood” as a guideline when determining what sorts of treatments may work with a particular patient.
Meaning, for a man, not getting morning wood can apparently be a sign of a physical problem.
Apparently many men who have trouble with impotence wake up with a boner, but when a partner is nearby, the boner goes away.
For patients that don’t get morning wood, drugs like Viagra have limited success.
The reason I know this, sadly, is because my 95 year old grandfather likes to talk about his sex life.
Trust me, if there was a practical way to bleach my brain, I would.
I’m sorry. 
Looks like Bernie already has an old mattress to stick his wood into.
That’s sick!
That’s his sister.
But besides that point – that’s sick!
Ouch. I didn’t realize it was his Sister. Double ouch. But you know what’s really sick? It’s making me laugh even harder.
As to the OP, Morning wood and having to pee has always been a coincidental phenomenon for me. In that I almost always have to pee when I awake. It just that sometimes there’s wood as well.
Yes. Yes I do.
Sometimes when I’m, you know, polishing the old love stick, I’ll have the TV on and the sound down. And sometimes I’ll glance up at the TV. And sometimes (here’s where it gets sick), a B&P will commercial will be on.
It shrinks down to Planck length, I tells ya.