I know that some (early ?) HD44780A's had a couple of bugs in them, but I can't really remember if this is one of those. The controllers that have these bugs fixed have an 'R' in one of the corners on the chip, so you might check that. Maybe you can find some additional info on the Hitachi site.

If I were you, I would just use the module with the timing parameters in the back of your head; the datasheet provides sufficient information to determine "worst case" timing.