Freak Overheating of "Plate Amp"

My inexpensive 50W, 8", Pioneer sub is left on "standby". One morning I smelled hot electronics when entering the kitchen. The sub resides under the table near where I sit. I could feel radiated heat and found the back of the sub was very hot upon touching.

It smelled and felt so hot I was surprised it was still functional after cool-down. That never happened again. Did the amp's fever "cure" its problem or does anyone have other theories. It was close to Halloween so maybe gremlins struck.
 
Caps might be ready to **** the bed? Like a pc it'll function after being disconnected and discharged but if it doesn't normally get egg cooking hot then it's probably on its way out. If you are curious then unscrew it and look for chard/burnt or swelled items...
 
The sub was almost new and still under warranty with no signs of char or overheating on the PCB. Because it worked fine after that incident and shipping to the nearest warranty service shop, in Chicago, was 200 miles away, creating a hefty cost-of-return, I kept the sub.

Four years later it's still cranking loud kitchen tunes when I succumb to KP duty. I let this and a larger Elac sub (almost the same design) have cooling breathers between several rockin' tunes as the back plate gets uncomfortable to touch. Jeez, a few cooling fins would have been worth the extra $$. Perhaps the components are cool with the heat, however, as they've both been crankin' for several years with only the one hiccup. At only $150 & $200 each, I suppose they're considered to be disposable.