[question timeline][1] returns

    "revision_guid": "335659EE-8983-4BEC-BACC-CC95784A4465"

[revisions by guid][2] return

    "revision_guid": "335659ee89834becbacccc95784a4465"


  [1]: https://api.stackexchange.com/docs/types/question-timeline
  [2]: https://api.stackexchange.com/docs/revisions-by-guids

Is there any particular reason for this inconsistency?