The Express's oil pump doesnt pump much. It doesnt need to.
So long as it's pumping and you dont have insane mileage on the bike, I suspect you're just fine.
If you really think it's a little slow you can add a tiny bit to your gas, or switch to a really high grade synthetic that doesnt need so much to do the same job.
Or if you're just paranoid you can bypass the oil injector all together and run straight premix. I just dont think you need to.