Macbook can't read sd card

Factual Questions
1

New Macbook Pro (bought March 2013), used to read my camera’s SD card just fine, now it doesn’t seem to read it at all. The icon doesn’t appear on my desktop, nor does it appear in the “devices” menu where it used to. Pulling it out doesn’t cause a “you pulled it out wrong” message to appear.

The card works as usual on my husband’s identical Macbook.

Is this a “be glad you are still under warrenty” thing?

2

Sounds like it, although you might just have a corrupted driver.
There’s no simple test for this that I can think of - you could try booting from the recovery partition, and then seeing if the SD card shows up in Disk Utility.

You could also look in the Console, and see if there are any messages about drivers failing to load, etc…