I've noticed it for many years, too. It's caused by an
unconcious impression that the Sun and Moon are about the
same distance away from you, even though the Sun is actually
400 times farther. That huge error in judging the distance
makes the angle look wrong.

Here is a pair of diagrams I made to show the geometry:

http://www.freemars.org/jeff2/SunMoon.png

They are not to scale, of course. In both diagrams, the
observer on Earth is at the "top" of the globe, with the Sun
near the horizon on the left, as shortly after sunrise, and the
Moon high overhead.

The diagram at upper-right shows the Sun and Moon as the same
size, since that is how they appear. In reality, the Sun is
400 times larger than the Moon.

The thing that makes the angle of the terminator look wrong
is the direction that sunlight appears to be coming from,
compared to the direction it is actually coming from.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves