It could be, however it is far more likely IMHO not to actually be a short.
The regs when calculating for short circuits assume that the short is of zero resistance. I would suspect that the hedge cutters blades resistance - it's not copper and not a clean cut[1]) did not allow a high enough current to pass to blow anything.
If you have a look at these
I believe that you could probably have a good 60A flash and not trip a
13A fuse or 32A MCB in 0.1 seconds. Just a big enough a flash and bang to scare you though. [1] Saying nothing but my finger really ougt to have had stitches after the new hedge cutter had a bite:-(