According to the following Twitter message it did, Just this afternoon.
wlynes - "My @caltrain NB 261 just hit somebody. It's going to be a long trip. No sudden stop immediately prior, he must have been timing it."
RyanInSF - "#caltrain the death train claims another victim"
cydeweyz - "Caltrain: The guy is dead. He's under the 5th train over.'"
juliunruly - "christ almighty. RT @caltrain Fatality on the tracks south of Milbrae T16:55."
nopayne - "God damnit, Caltrain, can't you go a single week without taking someone out? I'm rolling with BART today."
KCBSNews - "...Caltrain accident happened NORTHbound at Bellevue in San Mateo. All trains being held right now."
Also -- and it goes without saying, but we will -- Caltrain's schedule will be wonky today. Please reroute your way home, check your train times.