Should the batteries in my flash gun get hot?

It was a Canon Speedlite 270Ex on a Nikon D5100 with a Battery grip. I don't leave batteries in my flash gun so i got 2 fresh Duracell batteries from a pack and put them in the flash. I used my camera and flash for about 20 shots… I was putting my flash away and the flash and batteries were hot… (this was about 10seconds - 1 minute after use)

Before I started using an external battery pack for my flash… Yes the batteries would range from warm to hot. It would depend on the flash power setting and how quickly I was shooting.

Once I got an external battery pack, the flash batteries stay cool, as the only thing they power is the electronics and not the flash bulb itself (which is what uses up the power and heats up the batteries by having to charge up the flash capacitors).

It's perfectly normal.