I've been running in vibrams for around a year, gradually increasing speed and distance (to about 12 km)(a longer description of how I moved into vibrams is in this question). A few days ago I felt a sharp pain develop in what I think are my shins- the back of my leg, between the ankle and heel. I read here that shin splints are in the front of one's legs, and after reading this I thought maybe my Achilles tendon is to blame. When I tried running two or four days after this, the pain came back relatively quickly- before I had gone a single km.
UPDATE:
Even though that episode is behind me, it feels like my calves are super-sensitive now that I'm "barefoot" running. When running in regular shoes, if I started running fast (shortening my warm-up) I didn't feel like I was taking a crazy risk- but with vibrams it feels like if I skimp on the warm-up my calves are particularly likely to get pulled with disastrous results.
Does anyone else feel like the calves become unusually sensitive after switching to barefoot running?