Turns out that a previous fix caused this! Sorry about that, your images should be working fine now!
Details
Basically, a fix for a previous problem caused the behaviour you’ve noticed:
By setting vertical-align: baseline to post images, the images are aligned to the bottom of the baseline, which has a little extra space that in case of text, accounts for lettering that goes below it, like q, y, p, g and j. To fix it, I simply set vertical-align: bottom, which uses that extra space below.