Currently, old posts are displayed Mmm 'YY
and recent posts are displayed Mmm DD
Sometimes it’s hard to see the apostrophe that distinguishes a year from a day making it unclear when a comment was posted (was it the 15th of September this year? Or was it September 2015?)
I don’t have a specific preference on how one or both of the dates are changed but I think it would help if it was immediately obvious whether a comment was from a previous year or the current year.
Depending on consensus in the comments here I’ll probably lodge it as a request on github in a day or two.