OP, if the FSA crank is like some that i have seen, discrepancies in frame's BB shells are dealt with by use of a wavy washer, essentially a spring, like some Campy cranks. so most cranks could be considered laterally sprung. as the washer wears, it becomes less springy, finally resulting in a sloppy fit. if so, this may be what you are experiencing.
i wouldn't run it that way. i would disassemble and try a new wavy washer, if indeed the FSA crank that you have uses one. then i would try new bearings.
here's the type of wavy washer for use with an FSA crank i am referring to:
http://www.amazon.com/FSA-MegaExo-Li.../dp/B001GSSIUE
what i think can happen is this...
initially the spindle is a loose fit with the inside race of the BB bearings. after all, we can usually shove them in by hand. in addition to that lateral resistance there is the wavy washer. in most instances the two conspire to hide the laterally sprung nature of the design. with wear, the loose fit becomes looser and the wavy washer weakens, when that happens, both conspire to now reveal that the frame's BB shell is in fact too wide for the crank. the fix, as mentioned, may be a new wavy washer and new bearings.