pedestal sink leak

Hello, I recently decided to replace the pvc pipes on my pedestal sink. My wife and I elected to go with a brushed nickel finish kit and I did it myself. I cut all the pipes to match the original and assembled it without issue. Once I turned on the water and let it run, I noticed that there was a small leak coming from the last pipe that fits into the wall. It almost appears to be a case of the water backing up right at that point and then coming back vs. continuing down the drain in the wall. The only other change I made was I put up wainscotting, so there is a slight difference in the depth of the pipe coming out of the wall to the sink. Considering this, I allowed for extra length in the pipe when cutting it. I did not use any sort of seal when I put the pipe into the wall. Would this simply fix it? If so, what do I need to do?