Julia had the grace to look mildly guilty.

Occasionally, as now, when he thought about it, that fact made him feel mildly guilty.

She let herself go back to listening, even though she felt mildly guilty, like a sneak.

To be fair, Goodness did feel mildly guilty to be leaving her best friend behind.

Her mother sounded shocked and confused, and Maureen felt mildly guilty.

I feel mildly guilty about accepting such hospitality.

Then feeling mildly guilty for the outburst, she added, "I won't be long."

Annoying, prosperous, mildly guilty, but of no real consequence.

She felt mildly guilty of something- perhaps unworthiness.

He felt mildly guilty about taking it on; he really shouldn't take the time.