There's frequently no difference in actual meaning between the simple tenses and the continuous/progressive tenses. You could swap the verb forms in your two examples without any real effect.
As you might expect, the "continuous" tenses stress the continuing nature of the action. Of course there are certain particular verbs which don't work well in the continuous, or vice versa.
I wasn't expecting you to invite Mike to the apartment.
I didn't expect this phone call.