Is it normal to flinch at the beat-drop?

okay so this just started happening recently and I've only now caught onto what might be going on, whenever i'm listening to one of my favorite songs and the beat-drop comes, i always flinch or have a short spasm, my muscles all contract and i can't control them for a short time! and it's not like the drop startles me or scares me a bit because these are songs that i listen to on a daily basis, and know very well! and sometimes my right arm will just pulse and contract over and over, to the beat of the song! and i dunno if this info helps but my favorite artists are, Alan Walker, Marshmello and avicii. thank you

sorry for bad english