I've actually seen this occur quite frequently on 
Yahoo Japan. A couple times on eBay too.

What happened? The seller could've made a 
miscalculation when entering the opening bid. Not 
wanting to lose money on those cels, he/she 
cancelled and relisted the auction with a higher 
starting bid. Or the worst scenario would be that 
the seller got greedy and wanted more for those 
cels.

Is it allowed? You are always allowed to cancel 
an auction. And to relist it with a higher 
opening bid? Technically, yes. But it isn't 
something I, as a buyer, would want to see. If I 
see a seller doing that, I most likely won't bid 
on his/her auctions no matter how tempting 
his/her cels are.

Don't allow yourself to be too affected by this. 
Perhaps it's really an honest mistake on the 
seller's part. Giving others a benefit of a doubt 
will always make your life a lot brighter.