Expansion Prices Change without Warning?

For the second time in two days, I have been saving up coins to get expansions and the prices have gone up as if I'd skipped a level of expansion.

Yesterday, I saved up 120,000c and when I went to expand, it said the price was 150,000c. Today, when I first looked, it was 180,000c and when I tried to expand, it said the price was 200,000c.

The first time I thought, "Maybe I misread?" But twice? I know I hadn't expanded at the 180,000 level because I never had that many coins (ever) until today.

Did the prices really change in the hours between starting to save for the expansion and when the expansion actually occurred? Maybe this isn't a bug at all, in that case (though it would be rather annoying, nonetheless).

My storm8 id is rarrrkitty and I am using a Kindle Fire -- thus no screenshots (not that I would have known to take them anyway).

In the grand scheme of things, these random price jumps aren't a big deal, but I certainly don't want to get the the 1,000,000 level and have it jump to 2,000,000 or something....

Please note that changes to features or prices may occur as you continue to play the game. We continue to make adjustments to the game's economy and balance to ensure the prolonged quality of the game for both new and existing users.