Can't say I disagree with
@Shit Snacks , but can't help but think that a physical jarring from a drop would affect it physically. If there's been a change in resistance, something is different. For peace of mind, I would give her a good inspection, especially around the heater and screen above it. A good look down towards the heater with the screen removed to see if the spiral of the heater looks even and not out of place would make me feel better. Or better yet, if you've opened it up before, give the heater a good visual inspection.
My first unit was loosing power every few days and I was opening up and cleaning/adjusting connections. Over time the heater coil became unstable and I was getting much less power. I've still got the coil out on that unit, with visions of trying to rewrap it myself someday, unfortunately, I have many more plans than time to act on them