Interesting thing I noticed is when shooting glutes my right deltoid muscle twitches/spasms for a few second shortly after I am finished. Now my guess is this is due to me positioning myself kind of awkwardly for about a minute or a little longer so I can go ahead and keep steady while administering my injection. Now this happens here and there but today it happened in front of the mirror and I was pretty interested by it. Anybody else with similar experiences?