It shouldn't be a big deal

My two cents.
It is not very professional for him to use "shocked" here.  It sounds like a technique for negotiation. 
Ask him calmly why he was shocked.  Listen to what he says.  then explain calmly that your experience tells me that you rather negotiate after you see salary and benefit on paper.  With things these important you would like to avoid mis-communication.
Different company has different rules.  There is nothing to be shocked about.  When he being non-professional, he loses.