Metal Window Frame Rusting
Whenever you see metal rusting anywhere, it's usually not
going to be good news. Remember that metal rusts where moisture
accumulates for long periods of time.
If you noticed the basement window has a metal frame around it. The damage looks like it's at the top and bottom of the window frame, but the sides don't look as bad.
I wouldn't doubt that water sits on the top of the damaged window frame for long periods of time during the winter. If this window is located in an area where it snows, there's a good chance that the snow will accumulate around the base of the house and this snow should be removed regularly.
Most homeowners don't realize that snow creates more than just heating problems. Snow often accumulates on roofs and if this snow isn't removed, could form ice dams and ice dams lead to water damage.
If you see metal rusting, especially in a situation like this, you should find out what's causing the problem first, if possible. I don't suggest that you wait eight months until it snows before you make the repair, but it wouldn't be a bad idea to monitor the home repair, until you find out what's causing the damage.
Home Repair Tip: If you noticed the window is new and the metal frame is old. Obviously someone replaced the old window without making the necessary for home repairs. The metal frame should either be replaced or repaired and then repainted.
I don't know how long the homeowners expect the new window to last, but I doubt that the metal window frame will last the duration, if it's not repaired and maintained on a regular basis.