Question about model train

I recently purchased a Hornby Edward from Thomas and Friends. It is tender driven. I noticed that there was a burning smell while it was running. I took it to my local hobby store to have it serviced and looked at, and explained my concern. The guy looking at it said that this was common for "pancake" styled motors.

Was he right, or is there something wrong with the model I may not be aware of?Thanks everybody!