During the work week ours are always down because we use the laminator ALMOST every day. If we don't use it for a day, no big deal, never had an issue. I do raise them over the week-end, just in case.
Having said that, I was on vacation for 3 weeks this summer, and the rollers were left down the whole time, still no issues as far as I can tell. Still runs smooth. Seal 54 Base, at least 7 or 8 years old.