I used to do stuff like that (actually, that exactly) when playing HS ball. Then I finally got called for it and stopped doing it.
Later when I ended up coaching I'd chew out my lineman for doing it (happened more than once), and try to teach them better ways to be dirty without getting caught. :lol:
There's some rationale to doing stuff like this on OL*, but on DL it's just undisciplined.
Definitely intentional, though.
*On OL there's a point to dirtiness, as if you can get in a guy's head and get him steamed enough he'll just bull rush you, which makes your job easier in pass pro or run blocking b/c you already know exactly what he's going to do, and unless it's a run play coming up your butt you can just use his momentum against him. On D line you can't really be dirty enough to stop someone from trying to seel you or block you though, so it's just undisciplined to risk the penalty. .