yeah, it can be but you get used to it. also, I know it wasn't sparring but as you get better, you'll also take less damage from getting better defensively.
shouldn't be going hard in partner drills...especially without shinguards.
especially with guys like this lol...hopefully you're not in Africa. then again, I'm sure they take leg kicks better than I do:
this guy uploads literally the worst muay thai videos on the internet