Yeah your prob fine. I run a couple in the sump for my 180. A lot of the dry issues mostly came with the older glass sheath heaters like visatherms (2 shattered on me), but most now a days, and i did a quick check on yours have auto shut offs now.
I forgot to unplug a heater when I drained my tank and it actually melted the plastic holder and burnt some plants. The thing is still going strong 4 years later and it didn't shut off, obviously. It likely depends on quality of the heater and time it was on but I was fine.