Rails 3.1 / mysql2 error : "MySQL server has gone away"

I'm experiencing trouble upgrading my rails 2.3.14 / ruby 1.8.7 app to 3.1.1/1.9.2 : I have some (ActiveRecord::StatementInvalid) "Mysql2::Error: MySQL server has gone away" errors happening sporadically. It's important to precise that I never had such issues with the 'mysql' gem on 2.3.14 and the exactly same db (so the bug shouldn't come from mysql (v5.5.10)). Example : $ rails c production Load

[kattton]

resqueのdaemonを走らせるとMySQLとコネクションが無くなる。そしてバグ臭いので、対応を待つしか無いか。