Rasterize text, grey line appears

I am rasterizing text and selecting type optimized. When I do this, the resulting image has a faint grey line but it is not throughout the entire text (Michael doesn't have it and Radford does, see below). And it seems to only be happening with the font Bodoni 72 Smallcaps Book. 

I have found a work around for the time being. First expand then rasterize. It doesn't seem to be happening with the few other fonts I've tested or when I select art optimized. 

Any ideas how to fix? Thanks so much.