Slippery slope?

We were out of town for several days recently and when we returned, we found one of our soap dispensers had leaked soap all over. It's not the first time this has happened but it's the only one in the house that does this.

Why the other ones don't leak in this manner - not even its identical twin - is beyond me but what I think is happening is this soap dispenser is acting as a barometer.

" When air on the outside of the container presses harder (has higher pressure) than the air on the inside, everything stays put. Once in a while, air on the outside of the container presses less (has lower pressure) than air on the inside of the container. When that happens, the air pressure inside the bottle is enough to literally push the soap up the neck of the dispenser and out onto the sink . . . ."

Sure enough, it rained heavily all week. Also, the dispenser is more than half empty meaning it's more than half full of air which maybe accounts for why it doesn't happen all the time. I don't know but the next time it leaks, I'll remember to carry an umbrella.