Originally Posted by
Gnosis
I deem it likely that the right side of the crankset/chainrings has likely loosened (and may even have potentially deformed its machined taper)
This would be highly unlikely for this to happen the Bottom Bracket would need to be a square taper type, which for high end bikes has been obsolete for over a decade, the 2008 Tarmac Elite was spec'ed with an
FSA Gossamer MegaExo, 39/53 / FSA MegaEXO Bottom Bracket, which is an External BB type; and the OP indicated that these were still stock.