I am usually hesitant to second-guess someone else's time to perform a task, as it's hard to make a determination without personally being there.
  
As to the time needed to install a meter socket, it depends on many factors: was the electrician replacing an existing (working) one with another one? In that case, he may have had to do the work 'hot', which is very tricky and time-consuming; or he may have needed to get a work order approved by the utility beforehand to disconnect and reconnect the service, which also takes time. Additionally, was only the meter socket replaced? Usually there are other accessory parts, cables, etc. that must be changed out at the same time, since any new work must be done to the most recent Code requirements.

If I were you, speak with him anyway. If the bill is on the level, I'm sure he'd have no problem going over everything with you - I know I'd rather have the opportunity to explain an invoice that's perceived to be high, as opposed to having an unhappy customer.

More questions pending...