Hi David,
It looks like the datasheet tables and charts show the part's performance at typical design input and output conditions. While Vin=3.4V to 3.6V to Vout=3.3V may not be a typical design condition, the design can still work.
The LMZ10503 will be able to regulate 3.3 Vout at that input range but it may not be at the part's peak efficiency.