Don't know that much about MLPs, but is that sustainable, or just an abberation from the norm??
Your common mistake is to look at GAAP figures which do not actually reflect MLP free cash flow. You need to look for Adjusted EBITDA, and from these figures you will see that BBEP has room to grow the current distribution.
reading up on mlp's first will helphttp://www.naptp.org/documentlinks/Investor_Relations/WF_MLP_Primer_IV.pdf