Yeah, unless you are a fan of the "bounce and bite" that a straight is typically capable of... gauging a furrow in your face is not pleasant. I speak from it happening 3 weeks ago in the same, lazy circumstances.
While I find that it is more often linked to a dull blade, un-stretched skin can have a similar effect. It doesn't push through the hair, so you try a little harder, it suddenly gives, hops a little, then trenches in, only to be stopped by whatever piece of bone lies beneath... in my case, it was the cheekbone, just under the eye (up-stroke).
Definitely stretch the skin. It allows a much better gliding effect.