last time Tim Starling said I should ask in irc on current problems ... well, did so - no response in wikimedia-tech:
(23:52:49) Saibo: http://upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Sinai_Red_sea_ecological_disaster_Nabq_nature_reserve.jpg/120px-Sinai_Red_sea_ecological_disaster_Nabq_nature_reserve.jpg http://upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Sinai_Red_sea_ecological_disaster_Nabq_nature_reserve.jpg/121px-Sinai_Red_sea_ecological_disaster_Nabq_nature_reserve.jpg
(23:52:49) Saibo: compare ;-) Seems as if purge on upload of new version fails for some old thumb versions.
(23:53:14) Saibo: note: maybe this is only from Germany
(23:53:23) Saibo: as it happened some times in the past...
(23:53:32) Saibo: squids in Amsterdam were foul