This has happened to me with 2 orders so far. I create the ads, keywords, etc. At the pricing stage I put $0.15 in the box and apply to all keywords for a start. Everything seems OK. The next day, there's a budget pause and I find out I've been paying the max CPC for every page of keywords other than the first. Ends up costing me $4-$10 per click. This is why I set the budget at $5 now to start off, just in case. It doesn't happen every time either.