Short answer is "You'll be fine."

Your little/little sprocket combination hasn't changed. If your derailleur was taking up all of the chain slack before it will continue to do so. There's actually a chain sizing philosophy that says you should use the longest chain that your derailleur will take up the chain slack.

Your big/big combination has gotten smaller. Since your chain was long enough to safely cover the larger combination, it will obviously handle this.

Lots of people say that a new sprocket deserves a fresh chain. If your old drive line parts have extensive wear a new chainring might not mesh with the old chain and, if you replace the chain, it might not mesh with the rest of your old stuff.