Contactor: when and how to use it
The specifications on the linked website say the temperature range goes up to 80°C (though I'm unsure if that's operating or ambient). Either way, at 60°C you're within this range. In my experience, the main source of heat is from the coil and not the contacts so it is important to supply the proper coil voltage. Overvoltage or undervoltage will cause the coil to warm up more.

It is normal for a contactor to be on for a long duration of time. As an example, I just installed a ~77 A motor starter for a three-phase motor. A motor starter is nothing more than a contactor + overload and this motor will run almost 24/7. This should be no different for a DC motor.

With that said, everything is application dependant. The coil of the motor starter in my example is rated for continuous duty. Some contactors may not be suited for 24/7 operation. Some contactors don't like being opened and closed quickly. The important point is to examine the datasheet accompanied with the contactor and make sure that its specifications meet your requirements.



Edit: I missed the switching voltage of the contacts on the linked page. I had assumed it was at least your 48 VDC and the 12 VDC/14 VDC related to the coil. If you use contacts rated for 14 VDC at 48 VDC you'll run the risk of welding them shut. I'd advise finding a contactor with a higher contact rating.