Is there a word in the English language that means slightly surprised?
"Startled" carries a milder level of surprise than, say, "astounded". So one could be startled by someone jumping out at them, or by a cat suddenly swatting them with its paw when they didn't know it was next to them, or an unexpected loud noise. The meaning isn't just "surprise", though. Closest one I can think of, however.
'Mildly surprised' is how I'd express this idea. Sometimes a qualifying adverb plus the basic concept has to do the job of a precise verb.