Select the B and check what language is applied.
Is this a TOC being generated by ID?
Is ID fully patched? I don't think it's relevant, but it looks like you have a missing font (Museo Sans).
I should have stated, the screenshots are from a copy for testing, however the 'live' document exhibits exactly the same behaviours.
The TOC is generated by InDesign, here's the details:
The language is English:UK for everything. I've even deleted the existing frame and rebuilt it, but no success. Very strange!
The only thing obviously different about the listings here is that they come from different documents. I'd try exporting that doc to .idml and resaving as a new .indd (don't overwrite the old one), then use the new one to replace the old one in the .indb.
If that doesn't do it, then try deleting the text frame tha holds that heading and repalce it with a new one, and retype the heading.