I don't know, Claire, it sort of depends on how good your relationship is with your MIL. I lean towards saying something, but that's my new thing, expressing myself in places where I wouldn't have otherwise.
A long time ago, at my SIL's wedding, I was hurt that they gathered up the whole family for pictures, EXCEPT ME. MIL was just too flustered and busy posing to notice that the photographer was excluding me. I should have just inserted myself into the picture anyway, but I sulked instead. I explained it to H later, but by then it was too late, of course.
So....I might vote for sending a couple of pictures that include you, but I might also say something to your MIL that you noticed you weren't in any of the pics so far. She might not even realize it. Of course, then if the finished product still doesn't include you after you explained it, that's the point you'd need to "rise above gracefully."
