From where I sit looking out of the window on a daily basis it is a remarkably common occurence, and appears not to be limited to low hour pilots either.
Leaving the tow bar attached is probably number three in our local league of clangers. Number two is trying to taxy with the machine still tied down to the floor (either on one side or both). Number one is to actually achieve taxying speed with concrete blocks still tied on the wing or tail. This must happen at least three time per year around here.
As yet I haven't joined this league. My best to date was to start up an M-14P radial with exhaust pipe caps still attached (these home made large egg cup shape caps are a push fit to collect any oil that leaks whilst parked). Luckily they shot off the ends of the pipes and bounced harmlessly out of the way.
But if Mr Cubin can fall foul of the tow bar clanger then I cant see why I shouldn't.
(I have got into the habit now of getting down on my knees and looking for 'all clear' underneath as the last thing I do before climbing in. Get some strange looks sometimes from other people who seem to think I am praying to my favourite God)