Hi Paul, the Merbau will start to 'bleed' as it's the tannin coming out of the timber, and even though it may have been pre-oiled it won't have been done expensively and would have been done with a spray gun, not with a brush.
It bleeds after the rain which can stain any concrete around it leaving marked, one way to reduce this is to wash the panels down with 'deck cleaner', this will make it go away quickly and the more you hose it down the quicker the tannin or sap will disappear.
Keep on eye on the concrete and hose it down whenever you need to.
Cabots oil based is perfect, just wait a few weeks before you apply it this will stop the timber turning a greyish colour.
You might have seen cedar weather board houses, when they're new ait's a lovely colour, but if not painted with a product they turn an awful greyish colour, although it can be revived but that's just extra cost and effort.
I'm sure it looks like a beautiful colour.
Best thoughts.
Geoff.
