I'm not sure but I think that tomatoes are too acidic for hedgehogs. I know that citrus fruits are a no-no because of the citric acid so it would make sense that tomatoes are also not a good treat. I've heard that sweet potatoes, carrots, and green bell peppers are popular treats. Maybe you could try one of those?
However, if it's in the baby food, I doubt that it would be overly acidic. So I don't really see the harm in trying the baby food. Is it listed as the main ingredient? or is the tomato further down the list? If it's further down, it should be fine, especially since it's processed baby food.
(Though perhaps it might be good to wait for more responses, as I am not 100% sure on it all.)
Keep in mind, Tomatoes are part of the "Nightshade" family... the same family as eggplants and Poison Ivy. I wouldn't feed my hedgehog raw eggplants, I don't even eat raw eggplants, but if you guys are fine with tomatoes that might be ok...