I have let my lines sit for several months in my outdoor kegerator with no issues. I use a heavy duty line cleaner from Micro-matic, and I just let the liquid sit in the lines for an hour. So far, so good.
Give them a good clean and I'll bet you are OK.
"You canít be a real country unless you have a beer and an airline Ė it helps if you have some kind of football team, or some nuclear weapons but at the very least you need a beer"
- Frank Zappa