Heat exchanger wear under fuel tank?

I lifted my fuel tank on my 08 xp for cleaning. I noticed two small groves in the heat exchanger, just under the last ribs of the fuel tank.
Are they supposed to be there? Are they wear or are they put in at the factory? ( hard to see, didn't lift tank very high)
I looked under the tank of a 13 sport and there was no groves. There was also rubber matting under the 13. Was there a problem?
The groves are deeper than the ribs in the exchangers. Are they going to leak eventually?

Looks like BRP added a insulator mat or rubber pad under the tanks in 2010. I haven't heard of any leaking, but mine sure looks close.