The link to
automatically move this discussion to chat? is a smaller size than the preceeding text,
Please avoid extended discussions in comments. Would you like to. Shouldn't the whole block of text be the same size? At the very least, I don't think the size should change within the sentence (Would you like to automatically move this discussion to chat?)...
As you can see in the screenshots, this occurs on the mobile version of the site across many browsers (even a desktop browser). The text has a consistent size on the normal view, and the smaller size in the mobile view, matching the normal link size, leads me to the conclusion that this is a bug (i.e. unintentional).
On a phone:
The bug occurs in Opera Mobile 12, Firefox Mobile 14 and the Android 2.3 browser, on Android 2.3.
On a PC:
Firefox 13, mobile version of the site
On Firefox 13, desktop version of the site: