We have built an app on Thursday(21 Jan 2016), which was 3MB in size. Last night(27 Jan 2016) we have built the same app without changes for an production environment which was 5.1MB in size. We noticed new libs appeared in the APK. This has caused our app to behave differently than before (the 21 Jan build).
Is there something we need to do, to not have these changes in our app?
During those dates we were on a code freeze so while we did make a couple of changes they were very minor. If you have both APK's there are many reverse engineering tools for APK's on the market, you can inspect both and clarify why the size change happened.
Is it possibly due to reduced obfuscation or as Diamond suggested in the comments the inclusion of google play services?