Of course, there could be a chance that ice or rust is at play. If it’s a matter of ice, you simply need to warm your vehicle up for a few minutes and let the heat thaw the ice on your door. However, rust is a different story. Inspect your door, including the gaps and door handle. Signs of rusting will most likely require a full door replacement.
On the other hand, the solution could be as simple as replacing the seal on your door.