I'm in the midst of my first all-brett fermentation, so take my advice for what it's worth...
My beer started at 1.053 and finished (?) in two weeks at 1.008. I only used 0.4 lb acid malt, so I don't think pH is the problem (unless it was too low as Hoser suggested). Did you pitch a big enough starter? Note the White Labs vials contain a pretty low number of cells, optimized for use in the secondary, not the primary. I pitched a vial of brett lambicus and a vial of brett brux using a two-step starter. Assuming the Mr. Malty calculator works for brett, I think I pitched a std ale rate.
Also, what's your temp? I pitched at about 65 F. The fermentation did take a little longer to start, maybe 24-36 hours. It wasn't vigorous fermentation, and when it started to calm down after just a few days, I started to increase the temperature up to the mid 70s. At this point I got a second, more vigorous fermentation, and foam kept coming out of the air lock.
So, I'd say check your pitching rate, and perhaps add more brett if you think it was low. Also, you could try warming it up a little. I don't think brett will produce many fusels, so my understanding is a warmer temp is OK.