I confessed this afternoon to a substitute priest at my parish, Father being away. The priest, who seemed a friendly and jovial sort, absolved me immediately without asking for an Act of Contrition or imposing a penance. Was my Confession valid, and what do I do now?
Yes, your confession was valid. What do you do now? Just go on with your life.
Some priests will take it that the very fact that you are there is indication that you are contrite.
The priest should have given you a penance. If this happens again, just say “Father, what is my penance?” Last time I went to confession (2 days ago) the elderly priest forgot to give me a penance, so I said exactly what I quoted above and he gave me my penance. No big deal.
Everything is fine. You could say a few extra prayers yourself as penance, if it will make you feel better.