I will certainly get warm, but I wouldn't call it hot. "Hot" may mean that you ballast is failing or faulty. All ballasts produced for a very long time now have built-in overheating cutouts but it is still possible to get some melting of insulation or internal components.

I would call it hot rather than warm. I have two different brands which don't get a lot of use except this time of year.

Hot right where the ballast is and nowhere else.

Each spring I set my seed trays over the ballast of my 3 tube lights for cheap bottom heat required for some seed germination. Works great and the lights are lighting plant starts any way.