There has been a change to the fade-in in v7.01, it is now cached rather than being generated on the fly. This (from my testing at least) results in a significantly smoother preview, especially when the preview resolution is set to HD.
I exited VideoPad, and when I started it again, the problem with the fade-in cleared up
Makes sense, the cache should get deleted when VideoPad exits (assuming Options->Disk->Cache->Clear all Cache Files on Exit is selected). Meaning the cached fade-in got generated incorrectly the first time for some reason, but you were able to reset it by exiting VideoPad. We'll check for issues with the fade-in cache generation.
EDIT: Second thoughts actually. If you upgraded from v6.00 to v7.01, then what probably happened is that v7.01 was reading the old cache files generated from v6.00 (which did not preserve the fade). Therefore v7.01 did not show the fade. Re-generating the cache seems to have fixed the issue for you.