Knowing that it is very cold where you are in the mornings, I'm going to guess that you are experiencing the common fuel smell issue that only occurs during the extreme cold. Since the fuel lines are combinations of metal and rubber and those expand and contract differently, it is common to have small leaks especially around the rails. It usually only happens below 20F or so. That's my best $.02
We had 6 or 7 cars in the shop this week for the same thing. You can only find the leaks early when it is coldest and tighten up the clamps, or just tighten all of them. Some are very difficult to see, let alone tighten them !