According to the Post, the meal with the Frank staffer was what prompted Racalto to take concerns about Massa's behavior to Pelosi's staff.
Here, via The Hill, is the full statement:
Last year, a member of my committee staff reported to a member of my personal staff, Diego Sanchez, that former Congressman Massa had taken him to dinner. Diego quickly and appropriately reported that information to Maria Giesta, my Co-Chief of Staff for administrative matters. Although this was not an ethical violation, Maria did think it should be called to the attention of former Congressman Massa's Chief of Staff, Joe Racalto, a former colleague. Before she could tell Joe why she was calling, Joe said that he already knew about the situation and was considering how to address it.
I am proud of my staff for immediately responding in an appropriate manner to the information.