I recently had the opposite experience. I have a very cool basement that I ferment in, and I have a select few strains that I use that will survive in 53 degrees with the aid of an insulating blanket. I brewed with a friend a couple of weeks ago, and we used HIS yeast. After a week of solid activity in the primary, the bubbling stopped, and I transferred to the secondary. I didn't take a gravity reading because it was late, I didn't want to sanitize my theif, etc. After a week in the secondary, I decided to take a gravity reading. Getting close to bottling time, right? Wrong. Never any activity in the secondary, and the FG was 1.020. OG was 1.56. My friend took a reading on his batch (10 gallons, split) and his was 1.013 after fermenting at 68 degrees. Bottle bombs waiting to happen.
Three days ago I moved the secondary to my 4 day old 1800's vintage freezer converted to hot box at 65 degrees, and as of tonight I still had no activity, no decrease in gravity, and the nearest Wyeast or White Labs yeast is 2 hours away. Arghh! I made a quick starter with Nottingham and pitched it tonight. Hopefully it gets the gravity down, and I can bottle before it floculates out.
That said, I agree with Evan. Watch the gravity for a couple days, and RDWHAHB!