פרשת וארא - Non-believers

I had an interesting observation on כופרים from this past week's parsha:

For מכת ברד, the pasuk recounts:

ט:כ הַיָּרֵא אֶת-דְּבַר יְהוָה, מֵעַבְדֵי פַּרְעה--הֵנִיס אֶת-עֲבָדָיו וְאֶת-מִקְנֵהוּ, אֶל-הַבָּתִּים

However, the next pasuk, dealing with those who did not listen, reads:

וַאֲשֶׁר לא-שָׂם לִבּוֹ, אֶל-דְּבַר יְהוָה--וַיַּעֲזב אֶת-עֲבָדָיו וְאֶת-מִקְנֵהוּ, בַּשָּׂדֶה

Note that it does not begin וַאֲשֶׁר לא יָּרֵא אֶת-דְּבַר ה. The God-fearing are referred to as those who fear the word of God. However, the ones who did not listen simply did not take the word of God to heart. The way I understand this, it is not that the warning had no effect on him whatsoever. Deep down, there was a fear of the forthcoming plague. However, as many בעלי מוסר often teach, someone who fails to see the proper way is not because the truth is not there for them to see but rather, something inside is influencing them and convincing them not to see it. Likewise, here, inside, everyone knew that this plague was coming just as the first six did. But those who were not belivers at heart were able to convince themselves and turn their heart from the word of השם.