After applying pressure to glabella (Dysport treated), why does glabella get a muscle spasm and temporarily swell and turn pink?

After applying pressure to glabella, glabella area has an involuntary muscle contraction, gets unevenly puffy, and turns pink. It only lasts for a few seconds, doesn’t hurt, and doesn’t bother me. The 60 units in 11’s look like enough. This happened both times I’ve gotten Dysport (at 2 different offices). The 1st time I got Dysport, it started around month 2. The 2nd time, I noticed it starting shortly after getting it. I think it gets LESS pronounced the more the Dysport wears off. What’s going on?