If you were doing a group ride, it makes sense.

Headwinds increase the delta in effort between the riders pulling and those sitting in. The front rider may be doing 500w, the ones sitting in 150w.

On a tailwind you have to work more consistently. The rider pulling may do 500w again, but the ones following may have to do, say, 350w to follow.

Also the speed variance is smaller in a headwind, maybe not in percentage but definitely in mph. So you may go +/- 2 mph in the headwind (18-22 mph) but +/- 8 mph in the tailwind (26-34 mph).

When it's really windy in a flat race I usually get dropped in a tailwind bit. In fact my second last race I got shelled as we turned onto a tailwind section. The headwind was easier - I could sit in. Tailwind... not so much. This was with a couple really strong riders putting down the hammer, and they were probably going relatively steady.

If you were riding solo, then I chalk up your higher tailwind HR to glee and joy.