Can Apple replace my Macbook?

No one here can answer for Apple. Ultimately if you think it is that important you will need to contact Apple support or return it to an Apple store.

One question I might ask, however: can you prove that blemish existed before you unboxed it? That’s not an accusation, but something to be considered (along with the fact that it is an almost totally inconsequential flaw having zero impact on functionality).

Personally, I’d let it go.

Apple’s Return Policy

Apple allows eligible products purchased directly from Apple to be returned or exchanged within the applicable return window, subject to the terms and conditions of the relevant country or region. 

• Return eligibility: The return period, product condition requirements, and exclusions vary by region.
• Refund or exchange: Depending on the applicable policy, eligible returns may qualify for a refund or exchange.
• Original packaging: Keep the MacBook, included accessories, and packaging together, as these may be required for a return.
• Damaged or defective items: If you believe your MacBook arrived with a cosmetic defect, contact Apple promptly and explain the issue. Apple can assess the situation and advise on available options.
• Third-party purchases: If you purchased your MacBook from another retailer, you'll generally need to follow that retailer's return policy.

For details, visit Apple's official Returns & Refunds page and select the appropriate country or region.

Since your MacBook is only three days old, it's worth contacting Apple as soon as possible to ask whether a return or exchange is available.

this is the chip by the way, is it worth the hassle to go to apple and ask or should I just leave it be..

[Edited by Moderator]