Perth 1oz Gold, New Black Assay... Is It Fake?

I recently purchased this from a very reputable seller via ebay. Perhaps I'm being a bit paranoid, but something seems a bit fishy to me, and I'm hoping someone can shed some light here.

The bar in question certainly seems authentic. The packaging does not appear warped at all, and the bar doesn't appear to be overly thick (as far as I can tell).

But a couple details have me concerned...

First, the SN does not look like others I've seen that begin with the letter B. It is a bit off center, skewed, and the digits are narrower than usual.

Second, the kangaroo design on the reverse cuts in to the edge of the bar slightly in a couple areas. I know this was an indicator of a fake on older bars. However, the markings match identically when compared to a smaller size bar.

Third, there is a slight rattle in the package, the bar is not completely snug. Unsure if this is normal or something to worry about.

Considering this is from a reputable dealer, I may be making something out of nothing, but well, this is my first Au purchase and I'm hoping I didn't make a mistake shopping on ebay.

Thanks for any input you can provide!