I realized the solution AS SOON AS I was clicking the submit button but wanted to document this in case someone else ever has this issue. This is actually a bug in the neo4j-wrapper gem... that had a pull request merged two months ago... that I wrote. And I forgot about it. My local gemset still had my modified version of the gem cached, I guess, but the server was just using the latest release, which was done before my modification went in.
This bug is in type_converters.rb. Neo4j saves all times and dates to the DB as integers so it needs to convert whatever is submitted. The original code checked the type of the object to be converted. If it was a date, it converted it to a time and then ran utc; else, it just ran utc. This is obviously no good for strings, so my fix ran Time.parse(s) first.
So, if anyone else is having this issue and is using Neo4j.rb 2.3, add this line to your gemfile
gem 'neo4j-wrapper', git: 'https://github.com/andreasronge/neo4j-wrapper', ref: '00e5665ead'