There are a lot of reasons this may be. Your Internet may be faster than your average user's. You may be closer geographically to your server. Different browsers will show different load speeds. The site may be cached for you most of the time.

I know you weren't actually asking, but I figured it's worth stating this for someone else who might experience the same thing. Load times do vary greatly. Digging down into the Analytics can show you where/why they vary. And as you said and as always with Analytics, look for trends more than exact figures.