Having never flown before and having a parent who is a very fearful flier, I wouldn't expect them to have a different reaction. The only thing their reaction is a sign of is being normal, IMO.

A "little" nervous is just that: little. Play down the fear with your kids. Explain that you have an extremely irrational fear that is in no way indicative of the safety of air travel, and that they have absolutely nothing to be nervous about.