I don't know about more recent cranks but on FSA's earlier integrated spindle cranks, they recommended using Loctite 641 at the crank arm interface (after a lot of failures without it). The Loctite fills in any clearance gaps and results in a tighter, rigid fit between the components. I believe that SRAM is already using a press-fit for their crank arms but adding the Loctite certainly can't hurt. Good luck finding it at any bike shop or hardware store though. I ordered mine (to fix a friend's crank) from McMaster Carr.
To apply it, you must first clean off any grease from both the spindle and crank arm. Use acetone to get the surfaces completely clean. Apply the Loctite to the splines on the spindle and assemble. Takes 24 hours to cure. I'd be curious to hear if it solves your issue.