Yes it certainly is damage by leaf miners.

Based on the size of the leaves, is this something that was likely done in the past?

Depending on how long you have had the tree, the leaf miner damage could have been done at the nursery, Neem oil will have absolutely NO effect on the miners.

Only had the tree for about 1 week. I think it has to happen at the nursery. If not neem oil, is there something else? I've never had leaf miner before. I assume the offending miners are long gone by now, but is there something I should do for prevention?