Toyota 03 Camry AND 00 Avalon

I just changed the oil n filter for my 2003 Camry LE, and a 2000 Avalon XLS, both have automatic transmission. I used 10w 30 oil, 4 quarts for both vehicles.

What are the chances that after changing the oil for both vehicles that I would have the same problem.

when gear is put into drive, cars does not engage immediately. Once engaged, cars will rev with slight forward progress.

I do know how to do a basic oil n filter change. Do to time constraint I have been sending both vehicles to my local garge for basic oil changes. I did notice that both oil plugs were replaced with hex head plugs. Foul play from my local garage? Any assistance would be greatly appreciated.