The 1840 typesetter accidentally dropped the behold here. There is no motivation, grammatical or stylistic, for Joseph Smith to have omitted this instance of behold in his editing for that edition.
Elsewhere, the text has 32 occurrences of “and behold I”. There has been no tendency to remove the behold from these other instances; thus the omission in 1 Nephi 14:28 is clearly accidental. In accord with the reading of the printer’s manuscript, the 1908 RLDS edition restored behold to the RLDS text.
Summary: Maintain the use of behold in 1 Nephi 14:28 (“and behold I Nephi”); behold was accidentally dropped in the 1840 edition.