I got a 15-round 9mm mag and a 12-round s&w mag.

It will hold 16+1 rounds as opposed to 15+1, but it's hard to load and I'm thinking I want consistency in my mags, so I'm thinking I'll return it.  Plus I'm thinking it might not be 100% reliable like the factory 9mm should be.

Should I contact the dealer or go straight to SA to get a 9mm mag?

<edited to add>
It is a 4" Service model and is my first full size (as opposed to .22) handgun.

just buy the .40 xd to go with the mag!!!!

The new 9mm mags all hold 16+1.May require some lip tweeking but the bodys are all the same I would trade if I had a 9mm mag.I would first contact the seller maybe they swapped it with a 40 and have a 40 with a 9mm in a case.
Place to buy more mags www.pistol-gear.com or www.xd-hs2000.com for all of your XD needs.
Welcome to the Xd club I now have three

Damn,when I got my xd40 I also ordered another mag,for a total of three.The extra mag was a 9mm.I would ask if you would want to trade,however it is a blocked ten rounder.Someday the shop I ordered it from is supposed to get me a .40 twelve round mag.......

I'll give you a dollar for it and pay for the shipping........

They were probably mag swapping and messed up. When I bought my XD, after the ban expired I might add, mine came with 1 10 rnd and 1 12 rnd. I later suspected they were swapping 1 post mag from an XD with 1 no ban mag from the newly arrived XD's so buyers were at least getting 1 no ban mag with their XD even if it originally came with post bans. Only reason I suspect this is because mine was built after the ban expired, or my tinfoil has gone bad an they were just trying to get rid of 10 rnd mags at the factory.