the closer to 60dF, the more accurate your hydrometer is...
But since you used a refractometer, it shouldn't affect it as long as you have Automatic Temperature Compensation.
Mine does, and as far as I know, most do. But even if yours doens't it shouldn't have been too far off.
1.030 target gravity is awfully low for an extract kit, but I imagine that the 7 extra points should really only add about 0.5% abv to your end product.
Beer, happy Produce of our Isle/Can sinewy Strength impart,
And wearied with Fatigue and Toil/Can cheer each manly Heart.
Labour and Art upheld by Thee/Successfully advance,
We quaff Thy balmy Juice with Glee/And Water leave to France.
Genius of Health, thy grateful Taste/Rivals the Cup of Jove,
And warms each English generous Breast/With Liberty and Love!
(Rev James Townley, 1751)