Your solenoid's surface temp may not transfer directly to the hose. I

If you search the Web, you'll see multiple questions on this subject.

The magnet is relatively powerful because it's holding back a spring the has to close to keep you safe. Also, the liquid propane may freeze-up the valve otherwise?

Anyway, you might see if i) the hose fittings to the solenoid seem as hot; II) see the difference in amp draw (as others have noted) with the solenoid on, off, and the whole circuit energized; and iii) write or email the manufacturer, I'm sure they should give you comfort or quickly send you a replacement if it is unsafe.