In United States, the electrical code requires 12 gauge wires be used for wiring supporting 20 amps total. 14 gauge for 15 amp circuits. It's actually not as simple as this but this is the basic. Under sized wiring causes voltage drop, heat build-up, etc.
In some older homes, there were instances home owners needed more amperage delivered to their sockets. In some cases, home owner(s) just replaced the fuse and left the wiring alone and these were thin wires. That could be an issue. It's a little more difficult to do with circuit breakers, and if an electrician is involved, they will not do that.
I still haven't dared to plug it in our home, but after inspecting the prongs I noticed that one of the two flat prongs is splitting right at the tip where it folds back on itself. It's still connected, but a definite split is happening. This sure seems to be a strong suspect. That should be an easy enough fix for an electrition to perform.
What had actually happened was at the hotel I plugged it in, flipped the switch and saw the lights come on, tested if the plate heated, and then turned it off, but I think there is an 85% chance I unplugged it before actually switching it off (I'll consider my head slapped by all of you lol). That is when the lights went out and the switch stuck in the off position. From then on whenever I plugged it in, the lights went out.
You did this at a hotel room? I bet you made friends out of other residents and managers.... hehe.
Tell you what.... take it home and carefully inspect the cord itself and replace the plug. It's not a big deal. There are only 3 wires involved. You don't need an electrician for that. All you need is someone who has done it once or twice.
It's a heavy current device. As I said earlier, if the capacity of the circuit (ie. outlet) is marginal, unplugging or plugging it in can cause the circuit breaker to trip when there is nothing wrong with the device itself. Unplugging itself without turning it off isn't a problem. I do it all the time.
I checked mine. The plug is the original and I know what you are talking about. Don't rush to any conclusions. Take it home, put it in your garage (so if something should happen, you are on concrete floor and nothing burns) and plug it in and see what happens.