JW, sort of an aside, but I do love me a power-lam for bows like this.
One problem with making stacked sandwich with contrasting woods is they often have contrasting qualities. Like, some just sand so easily you can develop a dip or bump at the fades where they join. Some may expand with humidity like Pearl mentioned. Some want to cup once water based glue touches them, then shrink back when dry (goncalo alves does this so bad I started dunking the whole lam in water). All kinds of things.
Anyway, it's very likely creep or a shift like PatM says from the stack bending or flexing, etc. the glue squeezing even more. If you have confidence in your glue lines, don't worry about it.