Audio Sync issues after changing video clip frame rates

When shooting via my iphone 11 ProMax at 4K 30fps, I end up with a bunch of clips of varying rates from 29.9fps through to 30.1fps (approx). 

I figured it might be a good idea to highlight all the imported clips and change the frame rate to a uniform 30fps via <modify> / <interpret footage>.

After doing so, I seemed to have very slight audio sync issues and I even found that audio tracks for some clips were very slightly shorter than the linked video clip ..... which seemed weird but was presumably why there was a sync issue.

It seems like using my method to change the fps to 30 for all clips has maybe changed the video but left the audio as it was. Am I doing something wrong here ? Is it better to just leave the clips at varying frame rates ?