Usually the Earnings part of P/E is 0 in startup acquisitions, so technically the P/E ratio is undefined. 25x revenue isn't unheard of, though. It's not that odd either if you figure out what angle the acquirer is betting on. Often it involves a mix of:

- opportunity to easily cross-sell to a new swath of the market - continuing to grow the acquired business - realize economies of scale that the acquired business were working towards