There will naturally be variation in your times. That could be part of it.
But, two weeks off is a significant amount of time off. That could explain your 10 minute difference.
Here is a runner's rule of thumb: If you take X amount of time off, where 1 week <= X <= 4 weeks, when you resume, the time it will take to return to your previous level of conditioning will be 2X.
So, it could be another 4 weeks before you can consistently run a 5K in 27 minutes.
If you take less than a week off, you will lose little conditioning. If you take more than 4 weeks off, you will lose most of your conditioning.