Sonnet. IIII.
New yeare forth looking out of Janus gate,
Doth seeme to promise hope of new delight:
and bidding th'old Adieu, his passed date
Spenser, and Renaissance writers in general, seem to have just disliked the Roman numeral “V,” so Spenser will always write four as “IIII” instead of the traditional “IV.” 
 Note : Some believe the Renaissance writers didn’t know how to use Roman numerals properly, but this seems unlikely because Shakespeare and Spenser definitely read Ovid’s  Metamorphoses  and likely many other major Latin texts.  They just seemed to want to change the trend.
Amoretti: Sonnet 4