Normally, the 5-year warranty is given when retailers like ESH, Desa, etc partner with Sharp in any electrical, home or other expo.
If you buy the product at the expo, Sharp normally gives the 3-year extended warranty FOC and even subsidised further their partners so that can sell at cheaper price if compared from buying from their retail outlets.
This was what some of the promoters told me when I shopped around for ue630x last year

I might be wrong though, but no harm to call ESH and enquire