MC-E runtime good, could this be bad?

I tried searching too, but it couldn't answer the real question I have.

DealExtreme MC-E (21037) with a DealExtreme Trustfire black/fire 18650 just ran for 2hrs before I turned it off. Now, yes, the last half hour was significantly dimmer, but I thought that a setup like this wouldn't make it anywhere near that long. Might this suggest that I have a bad connection somewhere, or that my specific MC-E might be set up in such a way to favor runtime?

No multimeter or light meter (?) here, so I don't really know what's going on.

I get a little over an hour out of mine, before signs of dimming using moderate capacity Sanyo 18650 cells.

If you are using high quality 18650 cells, ~90 minutes to visual dimming seems about right.