High fuel consumption after purge valve repair?

My check engine light was on, so I took it to a mechanic. They said it was the purge valve that needed replacing, so I had them do that. However, in the three days since I have noticed that my fuel consumption is way higher. I have driven 25 miles or so and used almost a quarter of a tank. The mechanic said they would look at it and find out what else to fix, but it wasn't doing that before the repair! Could these be related at all?