Ordered two bike lights 2 weeks ago. The same day after placing the order, the seller sent me a message:

"Dear valued customer.

We have arranged a small gift to appreciate your order.
The gift and the product you bought were shipped by two separate packages,so it's possible that you receive one package earlier than the other.
Please feel free to contact us via eBay Message or reply to this email directly if any concern,we will be happy to offer help.
Thanks for being one of our customers.

Best Regards."

Yesterday I received a small flat envelope with some plastic pouches. The package has the exact same tracking number as my order, and on the envelope in the "Description of Contents" field is the name of the bike light, with "Qty 2". As a result, in my ebay account, the order status has become "Delivered". I promptly emailed the seller. Their reply:

"Sorry,we sent a free gift to you,the item you bought is sent in another parcel,could you kindly wait it till 25 Dec?"

What kind of seller would voluntarily send a free gift in a separate package from China, and using the tracking number for the supposed package for the actually ordered items so the actual order has no tracking info?

From the seller profile, they've opened the account for exactly 2 years, while most feedback is positive, some negative feedback comments mentioned similar issues. Looks like they use scams sporadically so that they would not be caught.