parsha stuma in mezuza
The norm is one of 3;
A. minhag sfarad [and many ashkenazim] place a space of 9 letters before ve'haya, but no space, or minimum space [3 or 4 letters only] after uvshe'arecha. This stuma is mentioned in SA OC 32 in regard to [the spacing before parshas vehaya in] tefilin, and they use the same idea for the same stuma in mezuza. This stuma is according to Rambam, that 9 letters space in the same line before the begining of the script is a stuma.
B. small space of less than 9 yudim after uvshe'aracha and same space before vhaya, so there is no 9 letter space in one line, and only a combination (b'tzeruf) of the 2 small spaces together there is a 9 letters spacing. This is a stuma according to Taz in tefilin, and many ashkenazim follow this opinion in mezuza as well.
C. 9 letters space after uvshe'arecha, and 9 letters space before v'haya. This is the Baal Hatanya's opinion in tefilin and mezuza, and this is the Chabad minhag.
Here the sofer left 9 letters after uvshe'arecha, and a small space of 2-3 letters before vehaya. There is no such minhag to space the stuma in mezuza (or tefilin).
But it is still kosher, since this is also a stuma according Rambam [hilchot sefer tora 8:2]. Even according to those that disagree with Rambam, and hold that this is a psucha (the 9 letter space after uvshe'arecha is dominent, and the 2-3 letter space is batel) a psucha is also accepted [bdieved] in mezuza.