The Resources tab says that my RB450G has 40 bad blocks. It’s brand new, I’ve just got it.
How does this affect me and what can I do?
re-install with netinstall
Anything under 100 is fine, but if you want to clear it, Netinstall will help
When i first bought 450G and updated into 4.8(through files menu),i’ve got 4 Bad Blocks,when i have did netinstall,the bad blocks still persist 
,the router only for couple days,should i RMA to my distributor?
Mine’s still 40 bad blocks and 41000 total sectors written.
As I said, 100 blocks is fine and will not affect how it operates.
Ok, that’s good to know.
Afterall, I’m very happy with it, no bottlenecks at 100mbps bandwidth(CPU@30-50%).