The young man came out looking rather pleased with himself but at the same time slightly guilty.

Apparently he felt slightly guilty about arriving an hour late.

She felt slightly guilty not to have thought about this much earlier.

He always felt slightly guilty that there were so few suitable for this role in the parish.

They looked slightly guilty as we came up, like kids caught with their hands in the cookie jar.

He feels slightly guilty for asking his friend to take him along on this Sunday afternoon.

I was proud of myself for finding it first, but also felt slightly guilty.

I felt very elated and slightly guilty at the same time.

The knowledge made him feel slightly guilty, but in no way spoilt his pleasure.

Otherwise I probably would have felt slightly guilty about this.