I'd say that's unlikely. The police check all relevant mobile phone records in the event of a serious motor accident, and I'm sure if it was a factor, it would have been reported and the driver would have got a much stiffer sentence.
Can they check something as specific as if your phone is unlocked (and for example, you're reading a text) at the time of impact?
I didn't think they could and I was under the impression it's quite hard to prove phone use without visual proof but I genuinely don't know.