Is it ok to drive in Sport mode in the first 500 miles?

I got my S4 Automatic last night. I have driven 100 miles so far in D only. Tonight coming home I put it into Sport mode for about 1 or 2 miles. It felt great.

Then I parked for 4 minutes, and then continued on in D. About 1/4 a mile later the car started to sound like it was working very hard, almost like it had the Emmergency break on. I kept checking and the Emmergency break was definitely not on at all. So I pulled over.

It then occurred to me that I had never driven so far without the radio on and wasn't sure what the engine usualy sounded like, so maybe I was just starting to hear for the first time the sound of the engine.

I kept going and went around the block a few times to see if things sounded normal.

Should I be concerned? I noticed compared to driving sport mode that the car feels to have a lag when in Drive mode. Is this normal? How often and how fast should I be driving in Sport? And is it ok to drive in Sport with only 100 miles on the car?

Last thing, I have always warmed my engine up before driving since receiving the car yesterday.